Signals Inbox·August 26, 2026·AgTech

What is Rainmaker doing exactly? Does it work?

Rainmaker is using drones, silver iodide and radar attribution to squeeze extra precipitation from suitable existing clouds. The science increasingly says the effect is real; the harder question is whether Rainmaker can turn it into enough measurable, useful water to matter at infrastructure scale.

Q1What is Rainmaker actually doing to make it rain?

Rainmaker uses drones to put silver iodide inside suitable existing clouds, then tracks whether those clouds produce extra rain or snow.

The basic process is surprisingly simple. Rainmaker's Stratus software watches weather conditions and tries to find clouds containing supercooled liquid water, meaning droplets that remain liquid below freezing. Its website says Stratus now combines more than 20 weather-data integrations and can identify promising seeding conditions several days ahead.

When the conditions look right, Rainmaker launches its Elijah drones directly into the target layer. The current aircraft can fly up to about 15,000 feet, stay airborne for around an hour and operate in temperatures down to roughly -20°C while dealing with severe icing. The drones release silver iodide particles, which give supercooled droplets a surface around which to freeze. Those ice crystals can then grow large enough to fall as snow or melt into rain.

The unusual part comes after the flight. Rainmaker records exactly where and when the silver iodide was released, then compares those tracks with NEXRAD radar, its own radar systems and satellite imagery. It looks for precipitation patterns that appear after the intervention and move downwind in a way consistent with the drone's flight path.

So Rainmaker's product combines three jobs that cloud-seeding operators historically handled much more loosely: deciding exactly when to seed, getting the seeding material into the right part of the cloud, and measuring what happened afterward.

How Rainmaker’s cloud-seeding system works

Q2Why does Rainmaker look more credible today than a year ago?

Rainmaker looks more convincing today because it is accumulating repeated observations of precipitation appearing after its drone flights instead of asking customers to trust seasonal statistical estimates alone.

Its biggest earlier announcement covered operations in Utah and Oregon. Rainmaker said it found 82 identifiable seeding signatures on radar and satellite corresponding to roughly 143 million gallons of additional precipitation. Those numbers came from Rainmaker itself, but the method resembles the physical-attribution approach developed by university and National Center for Atmospheric Research scientists during the SNOWIE experiment.

Rainmaker has now added a newer test in Alaska. During seven coordinated missions over roughly three hours, the company reported seven separate radar signatures following the seeding flights. That repetition is useful because one unusual radar feature can easily be dismissed as weather noise. Seeing a similar sequence several times under the same experiment makes that explanation less comfortable.

Commercial adoption has moved at the same time. Utah public records describe Rainmaker as a primary cloud-seeding contractor, and local water agencies have signed operational contracts rather than simply funding laboratory research. One southeastern Utah program, for example, contracted a six-month deployment involving four drones, two forward-deployed engineers and an operational meteorologist.

None of this settles the exact water yield. It does show that Rainmaker has progressed beyond a startup flying experimental drones and producing impressive videos. These days, the company is running real cloud-seeding programs while trying to build a measurable operating record around them.

Q3Can Rainmaker make it rain from a clear sky?

No, Rainmaker cannot create rain from a blue sky because its cloud-seeding system needs a suitable cloud to be there already.

That limitation gets lost easily when Rainmaker talks about "making rain." The company needs moisture, the correct temperatures and, for its best-proven technique, supercooled liquid water inside an existing cloud. Silver iodide changes what happens to some of that water; it does not supply the water itself.

The World Meteorological Organization draws the boundary very clearly. Its current weather-modification statement says humans cannot create a rain-producing cloud system from scratch, move enough atmospheric water vapor into a region to manufacture a storm, or eliminate major severe-weather systems through conventional weather modification.

Rainmaker therefore has days when the potential output is effectively zero. A drought can increase the value of extra precipitation while simultaneously making cloud-seeding opportunities scarcer if suitable storms stop arriving.

That constraint should shape how we think about the company. Rainmaker can squeeze additional precipitation from some weather systems. It cannot order those weather systems into existence.

Q4Does the cloud-seeding science behind Rainmaker actually work?

Yes, the cold-cloud seeding technique Rainmaker uses has strong evidence behind it when the atmospheric conditions are right.

For decades, cloud seeding had an awkward problem. Snow might increase after an operation, but weather changes naturally all the time, so proving that the seeding caused the increase was extremely difficult.

Recent experiments have improved that picture. The World Meteorological Organization now says winter glaciogenic seeding of suitable mountain clouds has shown an evidence-based causal relationship with precipitation enhancement. That is a much stronger conclusion than saying the idea is merely plausible.

The U.S. Government Accountability Office reached a more cautious conclusion when it reviewed the broader industry. Across the studies it examined, estimated precipitation increases ranged from 0% to 20%, and the GAO said reliable information on operational effectiveness remains limited. Utah's own long-running assessments have generally reported increases in the single digits to low teens, with state material historically citing roughly 5% to 15%.

Those findings fit together once we separate two questions. Scientists can now show that silver iodide sometimes changes suitable clouds and creates additional precipitation. We are much less precise when trying to say how much extra precipitation a normal operational program will produce across an entire winter.

Rainmaker is building on the part of cloud seeding that currently has the strongest scientific footing.

Q5What did SNOWIE prove about the science Rainmaker uses?

SNOWIE showed that scientists could watch seeded precipitation form inside a cloud and trace it toward the ground, giving Rainmaker a much stronger scientific foundation than older cloud-seeding programs had.

The 2017 SNOWIE experiment in Idaho used a seeding aircraft together with research aircraft, mobile radars and instruments on the ground. Researchers deliberately flew recognizable seeding tracks through suitable clouds. New radar echoes later appeared in corresponding patterns downwind.

The researchers could follow more than a visual pattern. Instruments detected supercooled liquid water being converted into unusually large concentrations of ice particles, watched those particles grow and then observed precipitation reaching the surface.

Three especially clean cases were later estimated to have generated roughly 100, 196 and 275 acre-feet of additional water. Together, that comes to about 571 acre-feet.

SNOWIE also exposed why this field remains difficult. The researchers seeded many more cases than those three. Natural snowfall often hid the artificial contribution so well that the effect could not be isolated cleanly on radar.

Rainmaker's core research idea follows directly from that limitation: make these recognizable, attributable cases routine enough that cloud seeding can be measured mission by mission rather than inferred only from seasonal statistics.

Q6Has Rainmaker actually proven that its drones create extra rain or snow?

Rainmaker has built a convincing case that some of its drone flights create additional precipitation, although the exact amount of water remains less certain than the existence of an effect.

The company's Utah and Oregon work is currently the largest dataset it has disclosed. Rainmaker reported 82 distinct radar or satellite signatures and estimated that those signatures represented about 143 million gallons of additional precipitation.

The methodology deserves to be taken seriously. Rainmaker records the drone's location, altitude and release time, then looks for precipitation developing in a matching position and moving with the surrounding winds. Independent atmospheric scientists interviewed by The Washington Post said the basic physical-attribution approach was scientifically credible and closely related to work pioneered during SNOWIE.

There is still an important distinction between credible evidence and a settled scientific result. The 82-signature dataset and the resulting gallon estimate were produced by Rainmaker. The complete work had not yet gone through the kind of independent peer review that would let outside researchers examine event selection, failed missions, uncertainty ranges and the conversion from radar reflectivity to precipitation.

So we are comfortable saying Rainmaker has probably demonstrated a real physical effect. We would not treat every gallon in its headline estimates as independently proven water yet.

Q7Does Rainmaker's new Alaska test really prove anything?

Yes, Rainmaker's latest Alaska test strengthens the case that its drone seeding produces a repeatable atmospheric effect, although it still comes from Rainmaker's own analysis.

The experiment is useful because Rainmaker ran seven coordinated missions and reported seven corresponding precipitation signatures on NEXRAD radar. The signatures appeared after the silver-iodide releases, moved with the surrounding winds and in several cases remained visible for more than an hour.

Rainmaker released about 374 grams of silver iodide during the experiment. Its quantitative precipitation model produced a central estimate of 57.6 acre-feet of additional precipitation, with the main ensemble estimates clustered around 45 to 65 acre-feet.

The weather was not perfectly clean. Weak natural precipitation was already falling, so Rainmaker had to estimate the background precipitation and subtract it before calculating the artificial contribution. The company also lists uncertainties around radar geometry, calibration, precipitation type, the boundaries drawn around each signature and what happened between the radar beam and the surface.

The repetition is more persuasive here than the 57.6-acre-foot headline. Seven similar outcomes following seven interventions are harder to explain away than one attractive radar image.

We should still want outsiders to reproduce the analysis. For now, the Alaska result makes Rainmaker's causal claim stronger without making the water-volume estimate definitive.

Q8Is Rainmaker measuring real water or just radar echoes?

Rainmaker is currently measuring atmospheric precipitation much better than it measures useful water arriving in rivers, reservoirs or aquifers.

Weather radar does not collect gallons of water. It measures the energy reflected by precipitation particles in the atmosphere. Researchers then use relationships between radar reflectivity and precipitation rate to estimate how much rain or snow those particles represent.

Rainmaker tries to handle that uncertainty by running an ensemble of different conversion relationships rather than relying on one equation. In the Alaska test, for example, it used 27 different radar-to-precipitation assumptions before arriving at its central estimate.

That is a reasonable way to estimate precipitation, but water managers ultimately care about what reaches the ground and where it goes next. Snow can sublimate. Rain can evaporate. Water can soak into soil, run into the wrong drainage or arrive at a time when it has little storage value.

Scientists interviewed by The Washington Post made exactly this point when discussing Rainmaker's earlier work. Ground precipitation gauges, snow measurements and streamflow data would make the attribution much stronger.

Rainmaker is now involved in research aimed at closing that gap. Its current research program includes ground instruments, hydrology and collaborations with groups involved in Utah's SNOWSCAPE work. If those projects can repeatedly connect a drone flight to extra precipitation on radar, extra snow on the ground and eventually extra streamflow, the company will have answered its hardest measurement problem.

Q9Can Rainmaker add enough water to matter at watershed scale?

Rainmaker can probably add useful water at watershed scale, but the volumes it has physically attributed so far remain tiny compared with the water systems it talks about restoring.

Rainmaker's 143-million-gallon Utah and Oregon result sounds enormous until we convert it into the unit water managers normally use. It equals roughly 439 acre-feet.

For comparison, Utah's recent Great Salt Lake planning has examined scenarios involving roughly 770,000 additional acre-feet of annual inflow to push the lake toward a much healthier elevation over the long term. Rainmaker's 439 physically attributed acre-feet equal about 0.06% of that annual amount.

The comparison is deliberately harsh because Rainmaker does not claim those 439 acre-feet represent all the water its operations generated. Most seeded precipitation may blend into naturally occurring snow or rain and become impossible to identify as a clean radar signature.

We can see that gap clearly in the Bear River Basin. Utah officials have estimated tens of thousands of acre-feet of seasonal precipitation enhancement from broader cloud-seeding operations, while Rainmaker has been able to physically isolate only a tiny fraction of that water mission by mission.

That is the gap. If the old seasonal models are broadly right, Rainmaker could eventually influence watersheds at meaningful scale. If customers insist on counting only water that can be physically attributed with high confidence, today's demonstrated output remains far smaller.

Rainmaker’s attributable water versus watershed-scale needs

Q10Are Rainmaker's drones actually better than planes and ground generators?

Rainmaker's drones clearly improve precision and reduce pilot risk, but we do not yet have enough public data to say they produce more water per dollar than every traditional cloud-seeding method.

Traditional programs commonly use ground generators or crewed aircraft. Ground generators burn seeding material and rely on winds to carry the particles into the correct part of a cloud. Aircraft can place material much more precisely but require pilots to operate near freezing clouds and severe icing.

Rainmaker's Elijah aircraft remove the person from that environment. The drones are designed specifically for in-cloud operations, can reach roughly 15,000 feet and carry sensors that tell the operator what conditions the aircraft is encountering.

The drones can also be dispatched in smaller increments. A water agency does not necessarily need to launch a crewed aircraft every time a narrow seeding window appears over one mountain range.

Utah's expansion of drone seeding suggests these advantages are useful outside a laboratory. State and local documents now describe broader deployments after earlier pilots, and Rainmaker is being contracted for multi-month operations with engineers stationed near the target areas.

The unresolved comparison is productivity. Rainmaker has not published enough data to let us compare incremental acre-feet per dollar, per flight hour or per gram of seeding material against a mature ground-generator network or a conventional aircraft program.

So drones look operationally better in several obvious ways. Whether they are economically superior will require a much more boring dataset, and that dataset is exactly what customers should want.

Q11Is Rainmaker already a real cloud-seeding business?

Yes, Rainmaker is currently a real cloud-seeding contractor with paying public-sector customers, even though research still makes up an unusually large part of the product.

The company was founded in 2023 and raised a $25 million Series A led by Lowercarbon Capital in 2025 after an earlier $6.3 million seed round. Since then, it has expanded operations across the western United States and embedded teams with water agencies.

Public records make the commercial activity concrete. A southeastern Utah agreement covered operations from November through April and specified four drones, two forward-deployed engineers, an operational meteorologist, monthly reports and access to Rainmaker's Stratus platform. Other Utah records describe Rainmaker as a primary cloud-seeding contractor for the state.

The interesting part is how much science the customer is buying alongside the seeding. Rainmaker employs radar meteorologists and atmospheric researchers, operates measurement equipment, develops precipitation-attribution software and is participating in broader research with university and government scientists.

At this stage, that combination makes sense. Rainmaker's commercial pitch gets much stronger if a water district can eventually pay for measured additional water instead of paying mainly for flight hours and trusting a seasonal model.

Today, Rainmaker has clearly crossed the line into a functioning business. What it has yet to show is that the economics can scale with the size of its ambition.

Q12Can Rainmaker make water cheaply enough to matter?

Rainmaker could have very attractive economics even with modest precipitation gains, but we still lack a trustworthy current cost per verified acre-foot from its drone system.

Cloud seeding has historically looked cheap on paper. Older Utah state evaluations estimated around $2 to $3 per additional acre-foot, based on modeled increases in runoff. Later state material continued to describe cloud seeding as one of Utah's cheapest ways to add water.

Those figures should not be plugged directly into a Rainmaker valuation model. The denominator was estimated additional water, rather than independently measured incremental water, and those programs relied heavily on older operating methods.

We can at least see what some Rainmaker operations cost. The southeastern Utah contract described above was worth $50,000 for a six-month program with four drones and a field team. What the public contract does not tell us is how many independently verified acre-feet that $50,000 eventually produced.

That missing ratio is more important than another large gallon announcement. If Rainmaker eventually shows that a $50,000 deployment reliably creates thousands of useful acre-feet, the economics become extremely attractive. If expensive instrumentation and drone operations generate only a few dozen attributable acre-feet, the story looks very different.

Water agencies already spend hundreds of dollars per acre-foot on some conservation, transfer and supply programs. Rainmaker does not need miraculous efficiency to compete. It needs credible numbers.

Q13Is the silver iodide Rainmaker uses actually safe?

Rainmaker's silver-iodide use appears safe at the concentrations used in cloud seeding today, according to the best government and scientific reviews we found.

The quantities involved are small. Rainmaker's entire Alaska experiment used only a few hundred grams of silver iodide spread through a huge volume of atmosphere and precipitation.

The GAO reviewed the recent literature and concluded that silver iodide does not appear to create an environmental or human-health concern at current cloud-seeding levels. The World Meteorological Organization reaches a similar conclusion: published studies have not found significant health or environmental effects from the amounts normally used.

We would still watch the question as Rainmaker grows. Both reviews leave room for more testing if operators begin using much larger quantities or introduce new seeding materials.

Utah is already moving in that direction by monitoring silver in snow, water, soil and sediments at extremely low concentrations. That is useful because safety evidence gathered from traditional programs should continue to be tested as deployment scales.

For today's Rainmaker operations, silver iodide looks much less controversial scientifically than the question of how much extra water the company actually produces.

Q14Could Rainmaker cause a flood or steal someone else's rain?

Rainmaker is extremely unlikely to create a major flood, while the question of smaller downwind effects deserves more research.

The clearest real-world example came after the catastrophic Texas floods in 2025. Rainmaker had seeded two clouds in Texas before the disaster, triggering claims that the company had caused the flooding. The seeding took place more than 100 miles from the hardest-hit area, the targeted clouds dissipated well before the destructive storm arrived, and meteorologists traced the flood to the natural weather system associated with the remnants of Tropical Storm Barry.

The physics also work against the flood theory. Cloud seeding tries to change precipitation efficiency by a few percent inside existing clouds. A catastrophic flood depends on a huge atmospheric system transporting and releasing vastly more moisture.

Rain stealing is harder to dismiss with the same confidence. The concern is that making water fall earlier in one location could theoretically leave less moisture for somewhere downwind.

Some long-term studies have actually found precipitation increases continuing beyond seeded target areas rather than obvious losses. Still, the World Meteorological Organization specifically lists unintended downwind effects as something that needs more research.

So we see very little evidence that Rainmaker can manufacture a disastrous storm. We are less certain about the small redistribution effects that could become important if cloud seeding expands across large interstate watersheds.

Q15Can Rainmaker work in hot, dry places too?

Rainmaker cannot yet claim the same level of proof in warm or highly convective clouds that it has for cold mountain cloud seeding.

The company's strongest science involves glaciogenic seeding. That means finding cold clouds containing supercooled liquid water and using silver iodide to encourage ice formation.

Unfortunately, many places with the worst water shortages do not spend enough of the year underneath that type of cloud.

Warm-cloud seeding uses a different approach, often adding hygroscopic particles that encourage small droplets to collide and grow. The problem is that warm convective clouds evolve extremely quickly and vary enormously on their own. A seeded thunderstorm can behave differently a few minutes later for dozens of reasons that have nothing to do with the intervention.

The World Meteorological Organization currently considers the evidence much harder to establish in those environments. Results from one type of cloud cannot simply be transferred to another region.

Rainmaker knows this. Convective rain enhancement is now one of its explicit research areas, alongside its much more mature glaciogenic work.

That could eventually expand Rainmaker's addressable geography dramatically. As of now, though, the company has its best case in places where suitable cold clouds already pass over mountains. We should not quietly extend that evidence to deserts and tropical storms.

Q16So, does Rainmaker actually work today?

Yes, Rainmaker works today in the specific sense that its cloud-seeding drones can make suitable existing clouds produce additional precipitation, and the evidence for that conclusion has become fairly strong.

We reach that judgment from several independent layers of evidence. The physical mechanism behind cold-cloud seeding is well established. SNOWIE showed researchers could directly follow artificially induced ice and snow. The World Meteorological Organization now recognizes a causal relationship for this type of seeding under suitable conditions. Rainmaker then took that methodology into commercial operations and has repeatedly observed precipitation patterns following its own drone releases.

The latest Alaska experiment pushes the evidence another step forward because Rainmaker reported seven radar-linked outcomes from seven coordinated missions. As seen above, the exact amount of water remains a company estimate, but repeated attribution is becoming much harder to write off as coincidence.

Where Rainmaker gets ahead of the evidence is scale. We still do not know how much useful water reaches the ground across a full season, how much enters the intended watershed, or what a verified acre-foot from the complete Rainmaker system really costs. Its directly attributed volumes remain tiny compared with something like restoring the Great Salt Lake.

So the answer is fairly clean. Rainmaker is doing something real, and its drones appear to work. The company has already moved beyond the old question of whether silver iodide can ever produce extra precipitation.

The important question now is whether Rainmaker can turn a real but modest weather effect into dependable water infrastructure. That requires thousands of missions, independent validation, ground measurements and eventually streamflow data showing that the water Rainmaker sees on radar actually becomes water people can use.

If Rainmaker proves that last step, its technology becomes much more interesting than cloud seeding has historically been. Until then, the science is ahead of the business case, and Rainmaker's biggest claims about ending drought remain much larger than what it has demonstrated.