The critical pre-flight step you’re probably not doing — and why it’s not as hard as you’d think

The following guest post about weather forecasting for drone flights was written by Emily Newton, who has eight years of experience creating tech articles for sites including DZone, TripWire and ReadWrite. When Emily isn’t writing, she enjoys reading and playing video games.

When you get a new drone, it can be tempting to get out and fly immediately. While you’ll want to start using it as soon as possible, consider that outside factors can turn an exciting flight into an expensive problem. Pre-flight planning, and in particular weather forecasting, is crucial for safe drone flights.

Inability to recognize potential weather hazards can limit your flight time at best — and damage your drone at worst. Learning how weather conditions affect drone performance and safety is critical.

Common weather patterns and how they impact drones

Here’s a closer look at how different kinds of weather impact drones.

Wind

Wind generally represents the chief resistance to your drone in the air. Drone propellers must work harder to maintain position and direction in higher winds, decreasing battery life.

Most drones have wind ratings between 4 and 14 meters per second, which translates to the ability to tolerate wind speeds of roughly 9-31 miles per hour (mph). For example, the DJI Mini 4 Pro has a maximum of 10.7 m/s. The Mavic 3 Pro is even more powerful at 12 m/s.

But while that technically means you can fly in those conditions, that’s nearing the maximum speed of many commercial quadcopters. Consequently, flying at even low speeds in 30 mph winds takes a similar toll on your battery as flying at your max.

While, you can’t always always tell the exact wind speed since they can change quickly, you can estimate it based on visual and auditory cues. A simple way to estimate wind speed is by doing a visual scan of common objects like leaves, branches or flags. Here’s a rough framework for how you can estimate wind speeds:

• 8-12 mph: leaves will blow up from the ground and flags will extend fully
• 13-18 mph: branches will begin to move
• 19-24 mph: Small trees begin to sway
• 25 mph+: You can hear whistling

Wind typically increases with altitude, so drones generally experience more resistance than pilots feel on the ground. Similarly, physical obstacles like buildings or trees can create turbulence, which drones experience as wind gusts.

Precipitation

Many drones are water-resistant, but that doesn’t mean waterproof. Heavy rains can slip between cracks to damage electrical components. Heavy rain or snow also introduces downward resistance, making drone motors work harder to maintain altitude and reducing battery life.

Moisture poses similar hazards. While rotors will work fine in fog or light snow, the resulting moisture buildup can damage drone sensors, especially sensitive optical components. 

Drones’ water resistance often comes as an IP rating, where the second numeral indicates liquid protection on a scale of zero to nine. A score of one is enough to resist vertical drops but nothing at an angle or pressure. Drones need at least a five to be safe in heavy rain. Otherwise, the pressure or direction could force water through their protective layers. 

But don’t assume every drone has an IP rating. If it doesn’t, that likely means it’s not even considered water-resistant. In fact, that’s the case for many top-tier drones. The DJI Mavic 3, for example, doesn’t have an IP rating at all, so don’t risk flying this drone even in mist.

Temperature and humidity

Temperatures can also pose unique hazards. Most batteries operate most efficiently around 68 degrees Fahrenheit. Colder temperatures increase electrical resistance, so flight times drop in the cold.

Specific flight times per battery level vary by drone, but here’s what to expect from your battery at different temperatures:

Efficiency doesn’t fall along a consistent scale. Instead, it gets more dramatic the colder it gets. Below zero, battery life becomes roughly half what it is at room temperature.

Batteries may be more efficient at higher temperatures, but the air is less dense. Consequently, drones produce less lift, meaning they can’t carry as much and have to work harder — decreasing battery life — to reach the same speed.

Humidity can also pose a challenge to drones, which have relatively delicate sensors. Higher humidity — which is more common in warmer temperatures — leads to moisture buildup in sensitive electronics. Some drones are more durable than others, so if you know you’ll be flying in moisture, it can be worth investing in a more rugged drone. On the other hand, some of the lower-cost consumer drones (including the DJI Mavic Mini and even the more advanced DJI Mavic Pro) have sometimes received criticism for not being able to tolerate moisture.

How to use weather forecasting to protect drones

Weather forecasting for drones is essential for safe and effective flights. Luckily, basic weather monitoring technology can protect your equipment.

Understand your drone’s limits

Know which conditions are too hazardous for your drone. Refer to the manufacturer’s instructions for a wind rating and IP score.

Avoid flying near maximum recommended conditions. For example, avoid winds more than two-thirds of the drone’s wind rating. That’s because gusts can introduce speeds at least 10 mph faster than average wind speeds, quickly taking conditions outside of those parameters.

Avoid flying in the rain if your drone has an IP rating below four. Even at a higher score, don’t sustain long flights in a downpour.

Use weather forecasting models

Using the right tools for weather forecasting for drones is important. Temperature and precipitation predictions are helpful but don’t offer enough on their own to inform safe usage.

Forecasting apps usually show humidity, air pressure, and wind speeds and directions. The National Weather Service is a great resource, including specific forecasts for aviation. Be sure to be as detailed as possible with your flying location for the most relevant data.

Other excellent forecasting tools include UAV Forecast, AccuWeather and Clime. They offer similar levels of information, so experiment with them to find which interface and additional features best suit your needs.

Plan flights for mild weather

Yet even the most accurate forecasting tools aren’t perfect, particularly when considering the aboveground but below-plane-level altitudes drones fly at. Consequently, err on the side of caution.

Only fly on days and times well below your drone’s safe operating range. Monitor how the weather progresses while you’re flying. Conditions can change quickly and extreme weather is becoming increasingly common, so quick responses to unexpected situations may be necessary.

Monitor drone conditions

Always monitor your drone’s state of repair. Pay attention to battery levels while flying, as these are the most susceptible to weather-related hazards. As a rule of thumb, start bringing your drone back for landing once your charge drops to 30%.

Before flying, inspect your drone for damage and charge its batteries. Remember to also charge them in warm temperatures to ensure they can recharge to full capacity. However, ensure they don’t get too hot, either. Lithium-polymer batteries, typically found in drones, lose capacity above 77 degrees Fahrenheit even faster than at lower temperatures. Extreme high-temperatures can lead to overheating and excessive voltages. 

When not using your drone, store it and its batteries in mild, dry conditions away from the elements. Regularly calibrate onboard sensors to ensure they remain consistent despite changing conditions.

Weather forecasting for drones keeps equipment safe

Consider the risks and follow these steps to account for weather-related hazards if you want your drone to last as long as possible. Understanding the importance of weather forecasting for drones is the first step in using this equipment more effectively. Doing that will give you more performance for your money.

–Guest post by Emily Newton