Can Airplanes Fly in Rain? What the Crew Can Still Undo

Yes. Commercial airliners fly in rain every day, and rain by itself almost never cancels a flight. Rain matters at two moments. On the runway, where water deeper than 1/8 inch (3 mm) can reduce braking force by as much as 77 percent, according to FAA Advisory Circular 91-79B. And inside a thunderstorm, where rain is the least dangerous thing present. Between those two moments, nearly every decision a crew makes in rain can be taken back: an approach abandoned, a landing turned into a go-around, a destination traded for the alternate airport the flight was fueled to reach under 14 CFR 121.639.

I clean painted clock dials, and have for over two decades, starting with the wall clocks in a Milwaukee railway station where a century of soot sat on numerals a wet cloth would have lifted in one pass. That trade teaches sequence: I test one corner with a cotton swab first, and what I am really asking is whether I can stop halfway and leave the dial no worse. I am not a pilot. I brought a reader's habit for standards documents, and aviation's are public. They describe a system built so its one irreversible action comes last, and rarely.

Rain does not stop the airplane. Water on the runway does.

Since October 2016, US airports certificated under 14 CFR Part 139 have reported runways using the FAA's Runway Condition Assessment Matrix, which assigns a code from 6 down to 0 for each third of the runway. Code 6 is dry. Code 5 covers damp through 1/8 inch of water, with braking reported as "good." Code 2 means flooded, more than 1/8 inch present and hydroplaning possible; braking drops to "medium to poor."

One-eighth of an inch separates them. AC 91-79B, issued August 28, 2023, calls that gap "dramatic," and Safety Alert for Operators 19003 puts a number on it: 30 to 40 percent of additional stopping distance may be required when a runway goes from wet to contaminated.

Hydroplaning is why the cliff is so steep. FAA Advisory Circular 25-31 gives the estimate outright: hydroplaning speed in knots is nine times the square root of tire pressure in pounds per square inch. A tire at 150 psi puts that near 110 knots, well inside a landing airliner's speed range.

Even below that speed, wet pavement is stingy. Under 14 CFR 25.109(c), an airplane on 200 psi tires gets a braking friction coefficient of 0.17 at 120 knots, rising to 0.30 by 60 knots. Snow and ice have their own rows; I am leaving them out.

How much rain is too much for flying?

Aviation weather reports have three words for rainfall rate, defined in Federal Meteorological Handbook No. 1: light is up to 0.10 inches per hour, moderate runs 0.11 to 0.30, heavy is anything above 0.30. Heavy is the top of the vocabulary, and that is the problem.

On May 12, 2026, the National Transportation Safety Board published Aviation Investigation Report AIR-26-04, built on 11 wet-runway overruns between 2008 and 2022. In six that happened while it was raining, intensity ran 1.3 to 20 times the heavy-rain threshold. The 2019 Boeing 737 overrun at Jacksonville, Florida saw 0.6 to 2.4 inches per hour; the 2016 Embraer 505 overrun at Sugar Land, Texas, 4.2 to 6.0. Both reached crews as the same word: heavy. The NTSB's three recommendations ask the FAA for descriptors above heavy, and for condition codes that fall progressively as the rate climbs rather than jumping from 5 to 2 at a depth nobody measures.

Engines are a separate question, and settled. Under 14 CFR 33.78 a turbine engine must run through 20.0 grams of water per cubic meter of air at sea level for three continuous minutes without flameout, unrecoverable surge, or loss of acceleration, and through hail for 30 seconds. That concentration comes from Appendix B to Part 33. Ordinary rain is nowhere near it.

The eight numbers that decide whether you fly

| Threshold | The number | Source | If crossed | |---|---|---|---| | Runway visual range | 1,800 ft standard Category I with touchdown-zone and centerline lighting; 1,400 ft special authorization; 1,200 ft Cat II; 300 ft Cat III | FAA Order 8400.13E | Approach not begun, or abandoned at decision altitude | | Cloud ceiling | 200 ft decision altitude on Cat I; a forecast ceiling under 2,000 ft forces the dispatcher to name an alternate | Order 8400.13E; 14 CFR 121.619 | No runway in sight at decision altitude: mandatory go-around | | Crosswind component | At least 20 kt or 0.2 VSR0, capped at 25 kt, demonstrated at certification; airlines publish higher | 14 CFR 25.237; AC 25-7D | Runway change, hold, or diversion | | Tailwind component | 10 kt working ceiling; more needs flight-manual approval, and the first 10 kt adds 21 percent to landing distance | AC 25-7D; AC 91-79B | Runway direction reversed, or the flight waits | | Runway braking condition | Codes 6 (dry) to 0; code 5 wet to 1/8 inch, code 2 flooded above it | FAA Runway Condition Assessment Matrix | Landing distance recalculated; it may not fit | | Precipitation rate | Heavy is more than 0.30 inches per hour | Federal Meteorological Handbook No. 1 | Assume code 2 on a smooth runway in moderate or heavy rain | | Wind-shear alerting | 45 Terminal Doppler Weather Radar systems covering 46 airports; no wind-shear accident at one since 1994 | FAA TDWR program | Approach discontinued or departure held | | Alternate-airport fuel | Destination, then the most distant alternate, then 45 minutes at normal cruise | 14 CFR 121.639 | The flight leaves already able to change its mind |

Read the last column. Seven of eight end in a delay, a hold, a heading change, or a landing elsewhere.

Rain compared with what actually turns a flight around

Summaries at the top of search results file rain and thunderstorms together, correct meteorologically and misleading operationally. The FAA's Aeronautical Information Manual notes that microbursts "commonly occur within the heavy rain portion of thunderstorms." Rain is the visible skin of the hazard, and collects the blame.

| Hazard | What it does | How it is found | The rule | Reversible? | |---|---|---|---|---| | Precipitation alone | Cuts visibility, floods the runway, degrades braking | Rain rate, runway condition report, prior braking report | Assume code 2 above 1/8 inch of water | Yes. Hold, go around, divert | | Wind shear and microburst | Downdrafts to 6,000 ft per minute; a 90-knot headwind-to-tailwind change across the microburst, within a few hundred feet of the ground | TDWR and LLWAS on the ground; airborne systems required by 14 CFR 121.358 | An alert triggers escape or a discontinued approach | Yes, caught early. That is the point of alerting | | Lightning | Punctures skin, disturbs avionics; an airliner averages about one strike a year | Radar, visual, storm electrification | Strike accidents are "extremely rare" per AC 00-24C | Yes. The flight normally continues | | Hail | Stones over 1/2 inch can significantly damage an aircraft in seconds, and fall miles from the cloud | Radar; hail always returns an echo | Avoid severe or intense echoes by at least 20 miles | Partly. The decision is; the sheet metal is not | | Turbulence | Shear turbulence up to 20 miles laterally from a severe storm; clear air 20 or more miles beyond the anvil | Radar, pilot reports, forecasts | Same 20-mile standoff; circumnavigate 6/10 coverage | Yes. Deviate or slow down |

Two details from AC 00-24C are worth carrying aboard. Gust fronts can run up to 15 miles ahead of the precipitation, which is why a visibly distant storm can close a runway. And inside a severe storm's updrafts, water concentrations can exceed what turbine engines are built to swallow, the one place rain itself is the threat.

Ground-based wind-shear detection is the clearest safety result here. The FAA's program page records 45 TDWR systems protecting 46 high-capacity airports across the United States and Puerto Rico, with no wind-shear accident at a covered airport since commissioning in 1994. The last was at Charlotte on July 2, 1994, before that radar was operating.

Where the reversible choices end

SAFO 19003, dated July 2, 2019, states it in one sentence: "Go-around, holding, or diversion may be necessary if rainfall intensity increases beyond what might be acceptable for the intended operation."

Before landing in rain, crews run a time-of-arrival landing assessment. The procedure in AC 91-79B and SAFO 19003:

1. Check the reported runway condition code and how old the last braking-action report is.
2. Compare rainfall intensity against that code. On a smooth runway in moderate or heavy rain, or a grooved runway in heavy rain, assume water deeper than 1/8 inch.
3. Recalculate landing distance using code 2, medium-to-poor braking.
4. Add a safety margin of at least 15 percent to the manual-braking distance.
5. If the result no longer fits the landing distance available, hold, divert, or go around.

Every step before number five can be repeated, revised, or discarded. Step five is the last exit.

You can watch a whole system take that exit at once. The FAA's account of July 17, 2019 in New York records 108 aircraft diverted, 57 in holding, 565 departure and 535 arrival cancellations in one day of storms. Each was a choice made while it was still one.

Touchdown is where reversibility runs out. Once the wheels are down, the runway is whatever length and friction it has. That is why the arithmetic happens beforehand, and why 1/8 inch of water gets a number.

Do flights get cancelled due to rain?

Rarely for rain alone. The FAA's NextGen weather program reports that weather caused 74.26 percent of system-impacting delays longer than 15 minutes from June 2017 to May 2023, from OPSNET records, with volume at 14.92 percent and runway unavailability 5.96 percent.

Where that lands depends on spare capacity more than rainfall. Newark and LaGuardia together logged almost 30,000 significant weather delays in 2022; Las Vegas near 8,000, Chicago over 5,000, Boston near 5,000. An airport near capacity cannot absorb a slowed arrival rate, so a shower becomes a schedule problem hours later.

Which of those numbers your flight sits inside on a given day, I cannot tell you. I have read the standards. I have not seen your dispatch release.

Frequently asked questions

Can a plane take off in heavy rain?

Usually yes. Heavy rain, defined as more than 0.30 inches per hour, does not by itself prohibit takeoff. The constraints are runway braking condition, crosswind and tailwind components, and visibility. Departures are held mainly for gust fronts and wind shear near the airport.

Does rain make turbulence worse?

Rain is not itself a source of turbulence. The convection that produces heavy rain is. FAA Advisory Circular 00-24C reports shear turbulence up to 20 miles laterally from a severe storm, and clear air 20 or more miles beyond the anvil. Steady frontal rain is typically smooth.

Why did my flight get delayed when it was only raining?

Rain lowers an airport's arrival rate. Aircraft need greater spacing on instrument approaches, and wet runways need longer landing distances. At an airport near capacity, that reduced rate creates holding and ground delays. The FAA attributes 74.26 percent of delays over 15 minutes to weather.

Can rain make an airplane engine stop?

Not in ordinary rain. Under 14 CFR 33.78, every turbine engine must keep running through 20.0 grams of water per cubic meter of air for three continuous minutes without flameout or unrecoverable surge. That far exceeds natural rainfall. The real risk sits in severe thunderstorm updrafts, which crews avoid.

Is landing in the rain dangerous?

It is routine, and managed by arithmetic. The controlling factor is water depth: above 1/8 inch the runway counts as flooded and stopping distance can rise 30 to 40 percent. Crews recompute landing distance before a wet approach and add at least 15 percent.

How do pilots see the runway in heavy rain?

Often they do not, until the last few hundred feet. Instrument approaches use runway visual range rather than eyesight alone. A standard Category I approach permits 1,800 feet of RVR with a 200-foot decision altitude; Category III goes as low as 300 feet with no decision height.