If there's anything South Floridians can learn from Hurricane Harvey, which caused catastrophic floods in the Houston area, it's that the right app could save your life. Now is the time to download any tool to keep you informed during Irma. Also, if you have battery banks, remember to charge them in case you need to charge your mobile devices later. Also, a USB car charger is useful after a storm if your home is without power.
Hurricane by American Red Cross. Let's be honest: A lot of TV-station-based hurricane-tracking apps seem like they are trying to scare you rather than inform you. The American Red Cross doesn't have to rely on ratings; instead, its mission is to keep you safe, which is all you can ask for. The app also helps you prepare for a hurricane, provides shelter locations, and gives you instructions on what to do after the storm has passed. Plus, it lets you check up on loved ones.
Zello. After Hurricane Harvey flooded the Houston area, Zello was the app residents used to ask for help when rising waters proved to be dangerous. Yes, this app literally saved lives. The chances that landlines and cell-phone towers work reliably after a major storm are slim. (Also, your Wi-Fi won't work if you don't have power and your cable line is down.) Zello gets around this by turning your phone into a walkie-talkie of sorts that can prove to be helpful if you are in need of assistance. (False claims that Zello works without any Wi-Fi or cellular data network have circulated on social media recently, but the app has still proven useful in emergency situations like hurricanes.) Another good option is also FireChat, which works using Bluetooth and peer-to-peer Wi-Fi to establish communication.
Waze. If you weren't here for the one-two punch of Hurricanes Katrina and Wilma in 2005, just know that getting around South Florida was a nightmare. Nonexistent traffic lights, fallen trees, and flooded streets meant traveling a couple of miles could take hours. Waze might make post-hurricane travel a bit easier thanks to its users, who share real-time traffic information with one another. That means you might be able to steer clear of all the obstacles left in Irma's wake.
GasBuddy. Fuel is already hard to come by. GasBuddy is normally used to find the cheapest gas in your vicinity via crowdsourcing, but the app also allows users to let each other know if gas is available and if a station has power.
Weather Underground. Of all the major online weather sources, Weather Underground tends to be the most even-keeled, meaning you won't get scaremongering, only the information you need to stay safe. There won't be any videos of reporters standing in the wind telling you how bad the storm is, which might make for great TV but isn't actually helpful.