How Grimes gets tornado and severe weather warnings.

When do the tornado sirens go off in Grimes?

The sirens are run by county emergency management, and because Grimes straddles the line, your siren is on the Polk or Dallas county system depending on your address. Both sound for a National Weather Service tornado warning or a severe thunderstorm warning with 70 mph or greater winds. They are meant to alert people who are outside to get indoors and check for more information, not as an all-clear or an indoor alert.

Siren issues: Polk County EMA 515-286-2107, Dallas County EMA 515-993-9894. Dallas County tests sirens the first Saturday of the month at noon.

When is the statewide tornado drill?

Iowa runs a statewide tornado drill each spring during Severe Weather Awareness Week, when sirens across the state sound on purpose. In 2026 it was Wednesday, March 25, at 10 a.m. Watch for the 2027 date in March, and use it to walk your family through where you'd go.

How do I get severe weather alerts in Grimes?

Sign up for at least two of these. Sirens are built to reach people outside, not to wake you up at 2 a.m.; your phone and a weather radio can.

• City of Grimes WENS (Wireless Emergency Notification System): text, voice call or email. It sends NOAA severe weather alerts, snow ordinance parking bans, boil orders and watermain breaks. Add your address to get location-based alerts. Sign up at grimesiowa.gov/alerts.
• Polk County Smart911 / Alert Iowa: free voice, text and email alerts for tornado, severe thunderstorm, flood, flash flood, high wind and blizzard warnings, plus evacuations and utility outages. Alert Iowa is the state's official emergency notification system. Sign up on the Polk County page.
• Dallas County addresses (the west side of town): sign up for Alert Iowa through Dallas County Emergency Management.
• A NOAA weather radio, the reliable overnight backup that wakes you up.
• A phone weather app with warnings turned on.

Where should I go when a tornado warning hits?

Go to a basement, safe room, or an interior room away from windows. That is the National Weather Service's advice, and it adds to bring pets if there's time.

• Mobile home: the NWS says mobile homes are not safe in a tornado. Get to a sturdy building right away.
• In the car: driving is not safe, but the best option is to drive to the closest shelter. If you can't, get down in the car and cover your head, or get out and find a low spot like a ditch.

We did not find a public tornado shelter listed by the City of Grimes, so pick your spot now at home, at work, and anywhere the kids spend the day.

Who issues the warnings for Grimes?

The National Weather Service Des Moines office is practically next door, at 9607 NW Beaver Dr. in Johnston. Its page, weather.gov/dmx, has the current watches and warnings and the radar. If you want to learn to read storms yourself, the office runs SKYWARN storm spotter training.

Severe weather in Grimes: FAQ

How does Grimes, Iowa warn people of tornadoes?

Grimes is covered by the Polk and Dallas county outdoor warning sirens, which sound for a tornado warning or a severe storm with winds of 70 mph or more. Since sirens are meant for people outdoors, residents should also sign up for the city's WENS alerts and Alert Iowa, and use a weather radio or phone alerts.

How do I sign up for severe weather alerts in Grimes?

Join the City of Grimes WENS alerts at grimesiowa.gov/alerts for text, voice or email notices, including NOAA severe weather alerts. Polk County residents can also sign up for Polk County Smart911 alerts, part of the state's Alert Iowa system, and Dallas County residents should sign up through their county. Back it up with a NOAA weather radio and phone weather alerts.

When are the tornado sirens tested?

Dallas County tests its sirens the first Saturday of the month at noon. Iowa also holds a statewide tornado drill during Severe Weather Awareness Week in March; in 2026 it was Wednesday, March 25, at 10 a.m.

Does Grimes have a public storm shelter?

We did not find a public tornado shelter listed by the City of Grimes. The National Weather Service advises going to a basement, safe room, or an interior room away from windows, and says mobile homes are not safe in a tornado.