This alert expired on 11 August 2026 at 09:45 UTC. It is kept here as a record.
It is the 2nd strongest of the 49 detections recorded within 20 km of this point since 15 April 2026. Another comparable one was recorded here earlier the same day. 8 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued August 11 at 4:05AM CDT until August 11 at 4:45AM CDT by NWS Chicago IL
An estimated 2,397,239 people live within 50 km of this point.
Nearby, since 15 April 2026
- July 27, 2026 · score 52 · 9.8 km
- August 11, 2026 · score 52 · 12.9 km
- August 10, 2026 · score 52 · 15.2 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 52 out of 100, at 82 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Event Data
| Type | Severe weather |
| Severity | medium |
| Calamity Score (ours) | 52 / 100 |
| Our confidence | 82% |
| Coordinates | 42.2240, -88.2980 |
| Nearest City | Crystal Lake (3 km) |
| Population Exposed | 2.4M within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-08-11T09:05:00.000Z |
| Source | https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.1f09c75fe6f762e5970311966febe5a09c710cc7.001.1 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Lake, IL; McHenry, IL |
| Headline | Severe Thunderstorm Warning issued August 11 at 4:05AM CDT until August 11 at 4:45AM CDT by NWS Chicago IL |
| Expires | 2026-08-11T04:45:00-05:00 |
| SenderName | NWS Chicago IL |
| HasExactCoords | true |
Safety Information
Always follow official guidance from your local emergency management agency. This platform provides scientific monitoring data and is not a substitute for official warnings. If you are in immediate danger, contact your local emergency number.
Series begins 10 February 2026. Comparisons refer to that period only. Collection gap: 14-26 August 2026.
This data is aggregated algorithmically from scientific sources. Not a replacement for official emergency warnings.
Want to know when something happens near Crystal Lake?
Calamity.live data shows a weather event with CalamityScore 52/100, near Crystal Lake (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 187 scientific monitoring sources.