Hi all, First off, I apologize in advance for the long post. Weather obviously plays a huge role in how your drone flies but it's not always clear how or why certain conditions affects your drone (especially for non-pilots). After researching online, on this forum, as well as from experienced operators, I've compiled some weather conditions you should look out for on your next flight. I believe even just having the basics down will open up a new set of tools for you to be confident that your next drone flight won’t go wrong because of weather conditions. An extremely important disclaimer: weather is finicky. No forecast or weather report will ever be more accurate than what you experience firsthand in the field. With that said, forecasts can be an incredibly useful tool for you to supplement your planning for individual operations as well as for long-term equipment maintenance. If I missed anything, please let me know! TL;DR: 1. Hot and Cold Temperatures 2. Precipitation 3. Fog 4. Humidity 5. Wind. Use your common sense and you will be okay. 1. Hot and Cold Temperatures Both hot and cold environments will cause adverse reactions for various components in your drone, resulting in reduced flight performance. If it’s a hot day, plan for shorter flights and longer downtime between flights. Why? In hotter environments your motors will need to work harder to generate more lift, which unsurprisingly causes shorter flight times. Not only that, but the generated heat could potentially overheat the electronics and/or melt the wired connections in some instances (this was an anecdotal story from an experienced operator I spoke with recently). Allowing for longer downtimes between flights gives your electronics time to cool down to a more stable temperature before taking it up again. If it’s a cold day, plan for shorter flights and monitor your battery closely while in-flight. Why? In colder environments the efficiency of your LiPo battery decreases. There is also a higher chance of your battery dropping below the critical voltage that will cut off the ESC’s/motors, so it’s best not to push the limits of your battery in cold conditions. 2. Precipitation Obviously, drones don’t hold up well in rain, sleet, or snow. If you’re out in the field and it’s raining even slightly, don’t fly — it’s not worth the risk. Checking the precipitation probability and precipitation intensity will help you predict the most likely conditions for that day. I emphasize “most likely” because, like all weather forecasting, you can never know what is going to happen. However, by planning ahead, you can prepare yourself for the most likely scenario. Most people have heard of precipitation probability and intensity, but I’d bet many people don’t truly know what each means. Precipitation probability: Precipitation probability is defined as the probability of precipitation at the given time and location. It is calculated by two variables: 1) the confidence that precipitation will occur anywhere in the forecasted area 2) the percentage of the area that will receive measurable precipitation. Multiplying these two percentages together yields the precipitation probability. For example: Let’s say there’s an 80% chance it will rain in 25% of Los Angeles, CA. There is also a 50% chance it will rain in another 25% area of Los Angeles, CA. In this scenario, the precipitation probability in the entire Los Angeles, CA area is: (80% x 25%) + (50% x 25%) = 32.5% Precipitation Intensity: Precipitation Intensity is the predicted intensity of precipitation, should it occur at all. It is measured in units of dBZ, ranging from 0 (no precipitation) to 75 (heaviest precipitation). Below is a generally-accepted scale of precipitation intensity that you can use to map quantitative ranges to a qualitative description. Use precipitation probability and intensity to dramatically help you plan in advance for the worst-case scenario. 3. Fog Fog may not get the same attention precipitation does, but it doesn’t mean it’s any less crucial to consider. Drones don’t handle any sort of moisture well, regardless of the form it comes in. I like to think of it this way: just because it’s a cloudy day doesn’t mean you won’t get sunburn. Just because it’s not raining doesn’t mean your drone won’t get wet. In both cases, you might actually bemore susceptible because you might overlook the conditions. How do you know there might be fog on any given day? Look at the visibility index. Visibility is measured as the distance at which an object or light can be clearly discerned and is defined as miles or kilometers depending on your measurement system. If visibility is less than 0.5 miles, it means there’s a high chance of fog. The equally bad part about fog is that you simply can’t see your drone past a certain point. And, with the current FAA laws, you’re prohibited from flying your drone Beyond Visual Line of Sight (BVLOS). With Part 107, the FAA requires that you have a 3-mile visibility from your control station! 4. Humidity There’s yet another weather metric that can get your drone wet: humidity. Humidity is defined as the amount of water vapor present in air and is expressed as a percentage of the amount needed for saturation at the same temperature. If humidity is close to 1, it means your drone might be coming back wet even if it’s clear and not raining. While humidity doesn’t pose nearly as much of a problem as precipitation or fog, it’s still something that you should monitor in the long-run. Long-term use in humid environments will have an effect on your equipment even if you don’t notice it from flight to flight. 5. Wind I won’t insult your intelligence by explaining what “wind” is. Instead, I’ll focus on what about wind you should be looking for. Higher wind speeds make it more difficult for your aircraft to hold its positioning, which will result in shorter flight times, less accurate position holds, and more difficult maneuvering. This makes sense: wind is a force that is telling your drone to go in a direction it doesn’t want to go — it’s going to have to work harder to maintain the same stability. Do not fly in gusts that may exceed your drone’s top speed. For a DJI Phantom 4, that’s 36 MPH (in ATTI, not Sport, Mode). For a DJI Inspire, that’s 49 MPH. The key here is to not fly in conditions where gusts may exceed your drone’s top speed, not just the average wind speed. The average wind for a given day might be 20 MPH but there might be gusts up to 40 MPH. That means you could be fine one second then lose complete control the next, blowing your drone into a nearby object while you stand there helpless. Wind of all things changes from second to second, and you never really know when the situation will turn for the worst. If there’s strong gusts that comes close to your drone’s top speed, prepare for the worst. Use Your Best Common Sense and You Will Be Okay I’d venture to say that many drone pilots know most, if not all, of the information that was presented in this post. If you didn’t, I hope the information you learned can help you fly safer in your future drone flights. Ultimately, you’ll always hear stories about how operators have pushed the boundaries of weather conditions and come out fine. In some of these cases, it’s not necessarily that the operator was being reckless or negligent. Some experienced pilots have a sixth sense about how weather will affect their aircraft, which gives them added confidence in certain situations that everything will be okay. However, for every story you’ll hear of flying in bad weather turning out fine, you’ll hear a few more where it simply didn’t. Pushing the boundaries doesn’t mean you’ll get burned every time, it just means your chances of getting burned goes up. And, the more you fly, the more the odds aren’t in your favor.