As an Amazon Associate I earn from qualifying purchases. Other affiliate programs also sponsor ads on this site.

Email share button  Facebook Share Button  Twitter Share Button  Reddit Share Button
Light Theme · Dark Theme

Suggestions for New Drone Pilots
Get Part 107 Training at Pilot Institute
Shop for Drone Bundles on Amazon
Find Pre-Owned Drones on eBay

Icing and Frost and How they Affect Your Drone

Ice forming on the edges of a drone propeller with the snowy ground in the background.

Icing is a buildup of ice on your drone. It can happen any time the temperature at your drone's altitude is a few degrees above to anywhere below the freezing point of water(32°F or 0°C). The risk of icing increases with the relative humidity.

Keep in mind that because temperature usually decreases with altitude, the temperature where your drone is flying is probably lower than the temperature where you're standing.

The biggest risk of icing occurs when there's also visible moisture in the air at or near the place where you're flying. For example, the risk of icing will be very high on a cold day when mist is rising from a lake that you're flying over, even if the air looks clear at your drone's altitude.

High humidity also increases the risk of your drone's propellers icing up, however, even if there's no visible moisture. The low-pressure area on the upper camber of the propellers, and the vortices produced by their tips, can cause moisture in humid air to condense into liquid water, which can accumulate on the propellers' surfaces even if the OAT (outside air temperature) is a few degrees above freezing.

The Importance of the Temperature / Dew Point Spread

The temperature at which the relative humidity will reach 100 percent is called the dew point. When the temperature and dew point are the same, visible fog or mist may start to form because at 100 percent relative humidity, the air is saturated and can't hold any more water.

That convergence point is also where ice or frost may start building up on your drone, especially on the props, even if you don't see any visible moisture from where you're standing on the ground. That's because the air temperature usually decreases with altitude and brings the temperature and dew point closer; and also because the spinning props cool the air.

Autel Evo II Pro 6K Drone Rugged Bundle ad links to purchase page at Amazon.

Because the dew point provided by weather information sources takes all of the weather conditions at a particular place and time into consideration, it's a very useful measure of the likelihood that your drone will experience icing or frost on a given flight. It's a very important weather factor that should always be part of flight planning on a winter day. The narrower the spread between the temperature and dew point, the more likely it is that your drone will experience icing or frost.

Personally, I consider a temperature / dew point spread of less than 5°F (3°C), to be high-risk for icing in cold weather. That's because the temperature typically drops with altitude, so the temperature / dew point spread at flight altitude usually will be closer at flight altitude than at launch altitude.

That's also why if I decide to fly on a day when the spread is exactly 5°F (3°C), I land frequently to check for icing and frost. I can't tell the temperature at altitude by looking at the sky.

Icing and Your Drone

On copter-type drones, the biggest risk areas for icing are the leading edges and lower cambers of the props, the air intakes and exhaust ports for the cooling fan, the camera gimbal, and the motor hubs. On fixed-wing drones, all of those areas plus the leading edges of the wings and stabilizers are at high risk for ice buildup. The picture at the top of this page shows actual icing on the prop of a drone.

Icing can also cause the gimbal to lock up. This can damage the gimbal control servos because they're constantly making minor corrections to stabilize the picture. A frozen gimbal is a reason to terminate a mission and land as soon as safely possible.

Some early warning signs that your drone may be icing up include:

If you notice any of these symptoms while flying on a cold day, land as soon as possible and inspect for icing. Icing can literally cause your drone to fall out of the sky and crash. It can also cause it to slowly descend into an area from which it can't be retrieved. So be careful.

You can reduce the risk of icing by:

Link to Pilot Institute Part 107 Commercial Drone Pilot course

If you do find icing on your drone, it's time to stop flying until the weather improves. You dodged one bullet. Don't push your luck.

Frost and Your Drone

A thin band of frost forming on the edges of a drone propeller.

Photo courtesy of Reddit user u/uaspandion.

I also start thinking about frost on cold days when the spread between the temperature and dew point is 5°F (3°C) or less, especially if the spread is narrowing. Under those conditions, there is a high risk of frost, even before the temperature and dew point converge.

Frost is a deposit of frozen water vapor that is more granular or crystalline than ice. It occurs when atmospheric water vapor touches a surface that is below the freezing point, and freezes without going through the liquid phase.

In other words, frost occurs when atmospheric moisture goes from the gas phase (water vapor) directly to the solid phase (ice) without becoming a liquid. It can be easily recognized by its rougher, crystalline texture.

Unlike icing, which usually forms on the props of a copter drone or the wings and tail of a fixed-wing drone, icing can form on any surface whose temperature is below the freezing point. Also unlike icing, you don't necessarily need visible moisture for frost to form. A combination of high humidity and low temperature is enough to trigger frost formation.

As with icing, finding frost on your sUAS is a good reason to call it a day. This is true even if the props aren't affected. Because of its rough surface, frost can accumulate rapidly as new frost adheres to the existing frost layer. Frost on the outside of your drone also means that it's possible that frost will form on the inside of your drone, where the electronics are. These are all good reasons to stop flying for the day if you find frost on your drone.

Revised May 20, 2023.


Special Offers
Get an Amazon Prime 30-Day Free Trial
Try a Kindle Unlimited Membership Plan
Create an Amazon Business Account for your Drone Business

Drone pilot flying a drone at a contruction site. An Autel drone flying over the frozen Hudson river. A large tablet mounted on a drone controller. A drone flying carrying a big bundle of cash underneath it. A DJI drone flying over a river in a wooded area. Man practicing maneuvering a drone A drone flying over a rural area. Hands of a beginner drone pilot holding the remote control. An aeronautical chart opened to the Central New York area.

The gray-bearded author outdoors with a wild bird on his shoulder and a Buy Me a Coffee tip link