⚡
Severe thunderstorm warnings are in the spotlight in 2025 as the U.S. faces a relentless severe weather season. From destructive winds and large hail to tornadoes and flash flooding, millions are under threat each spring and summer. Here’s your comprehensive guide to what a severe thunderstorm warning means, the science behind it, recent and historic storm impacts, and how to stay safe when severe weather strikes.
Check the Latest Severe Weather Alerts – NOAA/NWS
📰 2025 Severe Weather: Latest News, Outbreaks & Why Warnings Matter
🌪️ Memorial Day 2025: As millions celebrated outdoors, a slow-moving storm system brought severe thunderstorms, flooding, and tornadoes across the Plains, Southeast, and mid-Atlantic. Over 5.6 million people were at Level 3 risk on the SPC’s severe weather scale. Oklahoma, Missouri, and Florida saw major storm damage, rescues, and power outages. Localized flooding and wind damage struck the Mississippi Valley, with warnings issued for large hail and 70 mph winds.
🌀 May 2025 Tornado Outbreak: Between May 15–18, a historic outbreak spawned three EF3 tornadoes and one EF4, with Kentucky, Missouri, Illinois, and Arkansas suffering the most. At least 33 tornadoes were confirmed, causing $16 billion in damage and leaving over 600,000 without power. St. Louis alone saw thousands of buildings damaged, and 28 lives lost.
🌊 Spring 2025 Floods: April and May brought catastrophic flash flooding to the Ohio and Mississippi Valleys, with 8–12 inches of rain in some areas. Rivers overflowed, towns were inundated, and dozens were killed or injured. Flash flood warnings were often issued alongside severe thunderstorm warnings.
☔ Record Tornado Activity: By May, the U.S. had already seen over 730 tornadoes, well above average. The Storm Prediction Center expects 1,300–1,450 tornadoes in 2025, with the bulk in the Midwest, South, and Mississippi Valley.
🌩️ Derechos & Windstorms: Widespread straight-line wind events, called derechos, have caused hurricane-force gusts, widespread tree and property damage, and massive power outages from Texas to Pennsylvania.
🛰️ Climate & Meteorology: Meteorologists cite atmospheric rivers, polar vortex disruptions, and climate change as drivers of more intense and unpredictable severe weather, increasing the urgency for accurate warnings and community preparedness.
FOX Weather: Daily Severe Weather Coverage
🌀 May 2025 Tornado Outbreak: Between May 15–18, a historic outbreak spawned three EF3 tornadoes and one EF4, with Kentucky, Missouri, Illinois, and Arkansas suffering the most. At least 33 tornadoes were confirmed, causing $16 billion in damage and leaving over 600,000 without power. St. Louis alone saw thousands of buildings damaged, and 28 lives lost.
🌊 Spring 2025 Floods: April and May brought catastrophic flash flooding to the Ohio and Mississippi Valleys, with 8–12 inches of rain in some areas. Rivers overflowed, towns were inundated, and dozens were killed or injured. Flash flood warnings were often issued alongside severe thunderstorm warnings.
☔ Record Tornado Activity: By May, the U.S. had already seen over 730 tornadoes, well above average. The Storm Prediction Center expects 1,300–1,450 tornadoes in 2025, with the bulk in the Midwest, South, and Mississippi Valley.
🌩️ Derechos & Windstorms: Widespread straight-line wind events, called derechos, have caused hurricane-force gusts, widespread tree and property damage, and massive power outages from Texas to Pennsylvania.
🛰️ Climate & Meteorology: Meteorologists cite atmospheric rivers, polar vortex disruptions, and climate change as drivers of more intense and unpredictable severe weather, increasing the urgency for accurate warnings and community preparedness.
🌩️ What Is a Severe Thunderstorm Warning? Criteria, Categories & What to Expect
🚨 Definition: A severe thunderstorm warning is issued by the National Weather Service (NWS) when a severe thunderstorm is detected by radar or reported by spotters. It means severe weather is happening or imminent—take shelter immediately.
🟡 Criteria: In the U.S., a storm is “severe” if it produces:
⚠️ Difference from a Watch: A watch means conditions are favorable for severe storms; a warning means severe weather is happening or about to happen in your area—take action now.
NWS: Severe Thunderstorm Warning Categories
🟡 Criteria: In the U.S., a storm is “severe” if it produces:
- Winds of at least 58 mph (93 km/h)
- Hail at least 1 inch (2.5 cm) in diameter
- Or a tornado
- Base: 1" hail and/or 58 mph winds (standard warning)
- Considerable: 1.75" hail and/or 70 mph winds (higher risk)
- Destructive: 2.75" hail (baseball-sized) and/or 80 mph winds (triggers Wireless Emergency Alerts on phones)
⚠️ Difference from a Watch: A watch means conditions are favorable for severe storms; a warning means severe weather is happening or about to happen in your area—take action now.
🛡️ Hazards of Severe Thunderstorms: What to Watch For
🌬️ Damaging Winds: Can topple trees, power lines, and damage homes, causing flying debris hazards.
🧊 Hail: Ranges from pea-sized to baseball-sized, causing severe damage to vehicles, roofs, crops, and even injuries.
🌊 Flash Flooding: Heavy rain can quickly flood roads, creeks, and low-lying areas. Most flood deaths occur in vehicles.
🌪️ Tornadoes: Severe storms can spawn tornadoes with little or no warning.
⚡ Lightning: Strikes can cause fires, injuries, and fatalities.
🚗 Hazardous Driving: Reduced visibility, hydroplaning, and debris make travel dangerous during storms.
🏚️ Infrastructure Damage: Power outages, road closures, and damage to schools, hospitals, and public facilities are common after severe storms.
Ready.gov: Thunderstorm & Lightning Safety
🧊 Hail: Ranges from pea-sized to baseball-sized, causing severe damage to vehicles, roofs, crops, and even injuries.
🌊 Flash Flooding: Heavy rain can quickly flood roads, creeks, and low-lying areas. Most flood deaths occur in vehicles.
🌪️ Tornadoes: Severe storms can spawn tornadoes with little or no warning.
⚡ Lightning: Strikes can cause fires, injuries, and fatalities.
🚗 Hazardous Driving: Reduced visibility, hydroplaning, and debris make travel dangerous during storms.
🏚️ Infrastructure Damage: Power outages, road closures, and damage to schools, hospitals, and public facilities are common after severe storms.
📝 Safety Checklist: What to Do Before, During & After a Severe Thunderstorm Warning
🟢 Before the Storm:
Mass.gov: Thunderstorm & Lightning Safety Tips
- Check the weather forecast before outdoor activities
- Sign up for NOAA Weather Radio and local alerts
- Prepare an emergency kit: flashlight, batteries, food, water, first aid, radio
- Secure or bring in outdoor items (furniture, grills, toys)
- Trim trees and branches near your home
- Plan where to shelter—preferably a basement or interior room away from windows
- Go indoors immediately—avoid windows and glass doors
- Postpone travel; don’t drive through flooded roads (“Turn Around, Don’t Drown!”)
- Unplug electronics and avoid using corded phones
- Stay away from plumbing and running water
- If caught outside, seek shelter in a sturdy building or hardtop car
- If in a mobile home, move to a stronger shelter if possible
- Monitor local media and official alerts for updates
- Stay indoors until storms have fully passed
- Watch for downed power lines and report them—never touch them
- Check on neighbors, especially elderly or disabled
- Document any damage for insurance
- Continue to monitor for flash flooding or new warnings
📚 Severe Thunderstorm Warning FAQ & Key Terms
Q: What’s the difference between a severe thunderstorm watch and warning?
A: A watch means conditions are favorable for severe storms; a warning means severe weather is happening or imminent—take shelter now.
Q: What triggers a severe thunderstorm warning?
A: Radar or spotter reports of 58+ mph winds, 1”+ hail, or a tornado.
Q: What should I do during a warning?
A: Go indoors, avoid windows, stay off roads, and monitor alerts.
Q: Can severe thunderstorms produce tornadoes?
A: Yes—some tornadoes form with little or no warning during severe storms.
Q: What are the biggest dangers?
A: Damaging winds, hail, flash flooding, tornadoes, lightning, and flying debris.
Q: How can I get alerts?
A: Sign up for NOAA Weather Radio, Wireless Emergency Alerts, and local alert systems.
Q: What’s a “destructive” thunderstorm warning?
A: The highest category—baseball-size hail or 80+ mph winds. Triggers phone alerts.
A: A watch means conditions are favorable for severe storms; a warning means severe weather is happening or imminent—take shelter now.
Q: What triggers a severe thunderstorm warning?
A: Radar or spotter reports of 58+ mph winds, 1”+ hail, or a tornado.
Q: What should I do during a warning?
A: Go indoors, avoid windows, stay off roads, and monitor alerts.
Q: Can severe thunderstorms produce tornadoes?
A: Yes—some tornadoes form with little or no warning during severe storms.
Q: What are the biggest dangers?
A: Damaging winds, hail, flash flooding, tornadoes, lightning, and flying debris.
Q: How can I get alerts?
A: Sign up for NOAA Weather Radio, Wireless Emergency Alerts, and local alert systems.
Q: What’s a “destructive” thunderstorm warning?
A: The highest category—baseball-size hail or 80+ mph winds. Triggers phone alerts.
🔗 Official Resources & Useful Links
NOAA/NWS: National Weather Service
Ready.gov: Thunderstorm Safety
FOX Weather: Daily Severe Weather
Mass.gov: Safety Tips
NWS: Warning Updates
©️ 2025 | Severe Thunderstorm Warning: Complete Guide for US Readers