In short
Tornadoes, hurricanes, heat, wildfire smoke, winter storms, earthquakes and floods: where they happen, watch vs warning, and what to do.
The US has more kinds of extreme weather than most countries. Learn the ones for your area in your first week.
The National Weather Service uses two key words:
Watch: conditions are right for the danger. Get ready.
Warning: the danger is happening or very close. Act now.
Your phone receives Wireless Emergency Alerts with a loud sound. Keep them turned on. Also install a weather app, and sign up for your county's alerts.
Tornadoes (Great Plains, Midwest, South, mainly spring)
A tornado is a fast spinning column of wind. When there is a tornado warning or sirens sound:
Go to a basement, or a small room with no windows on the lowest floor (bathroom, closet, hallway).
Cover your head and neck. Wear shoes.
Mobile homes and cars are not safe. Go to a sturdy building.
Hurricanes (Gulf and Atlantic coasts, June 1 to November 30)
Hurricanes bring strong wind, heavy rain and storm surge (sea water pushed onto land), which causes most deaths.
Know your evacuation zone (search your county name and "evacuation zone").
If officials tell you to evacuate, go.
Before the season, prepare your kit and a plan for where to stay.
Extreme heat (the South, Southwest, and heat waves everywhere)
Drink water often. Stay in air-conditioning during the hottest hours; libraries and cooling centers are free.
Signs of heat stroke: very high body temperature, confusion, fainting. Call 911.
Never leave children or pets in a car.
Wildfire smoke (the West, but smoke travels far)
Check the Air Quality Index (AQI) at airnow.gov. Above 150 is unhealthy for everyone.
Stay indoors with windows closed. A N95 mask filters smoke; cloth masks do not.
If told to evacuate because of fire, leave immediately.
Winter storms (North, Midwest, mountains)
Stay off roads during storms. Keep a blanket, water and a shovel in the car.
Watch for frostbite and hypothermia (body too cold).
Never use a gas stove, grill or generator indoors for heat (see the guide on carbon monoxide).
Earthquakes (California, the Pacific Northwest, Alaska, and other areas)
When shaking starts: Drop, Cover, Hold On. Drop to your hands and knees, cover your head under a sturdy table, and hold on until shaking stops. Do not run outside during shaking.
Floods (anywhere, including in cities)
Turn Around, Don't Drown. Six inches of moving water can knock you down. One foot of moving water can carry away most cars.
Never drive through water on a road. You cannot see how deep it is or whether the road is gone.
Turning off emergency alerts because they are loud.
Going outside to watch or film a tornado.
Driving into a flooded underpass.