Severe Weather near Fond du Lac
Right now
The most recent data we hold from NOAA arrived 50 minutes ago, and this point is not in it. We record detections, not passes: an absence is not proof that nothing is there.
Nothing else has been detected within 20 km in the last 24 hours.
This alert expired on 4 September 2026 at 06:45 UTC. It is kept here as a record.
No stronger detection stands among the 28 recorded within 20 km of this point since 16 March 2026 — 19 others scored the same. Another comparable one was recorded here earlier the same day.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued September 4 at 1:23AM CDT until September 4 at 1:45AM CDT by NWS Green Bay WI
Urban PEI: 166,975 within a heuristic 50 km radius; not unique people.
Nearby, since 16 March 2026
- July 1, 2026 · 3.4 km
- June 10, 2026 · 4.6 km
- July 9, 2026 · 7.6 km
How we know
3 recorded sources include NOAA; independence is not established by this count.
Our own score for this event is 49 out of 100.
This is our versioned heuristic index, not source severity or a calibrated probability. Urban PEI does not count unique people.
Computed under scoring rules v4. Rows carrying other versions were judged by different rules and are not directly comparable.
Series begins 8 March 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.
Event data
| Type | Severe Weather |
| Severity | High |
| Calamity Score (ours) | 49 / 100 |
| Legacy data-support index | 0.92/1 |
| Coordinates | 43.7552, -88.3397 |
| Nearest city | Fond du Lac (9 km) |
| Urban exposure index (PEI) | 167.0K within 50 km |
| Impact tier | severe |
| Timestamp | 2026-09-04T06:23:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.576803487a0ed8cbd87fe58f2ab5445192423229.001.1 |
| Licence | US public domain · NOAA National Weather Service |
Physical priority index · v4 (historical). Heuristic priority, not calibrated probability, predictive accuracy or damage. The legacy data-support index combines assigned source support and field availability. Urban PEI is distance-weighted and does not count unique people; zero does not establish that nobody is present. Model cards.
Source and revision timeline
Source: noaa. Occurrence: 2026-09-04T06:23:00.000Z.
First archived: 2026-09-04T06:28:59.559Z. Material modification: not recorded.
Retained revisions are prospective; earlier versions may be unavailable. No revision entry does not prove that a record never changed.
Score breakdown
Technical details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Portage, WI; Waupaca, WI; Waushara, WI; Winnebago, WI; Fond du Lac, WI; Sheboygan, WI; Milwaukee, WI; Ozaukee, WI |
| Headline | Severe Thunderstorm Warning issued September 4 at 1:23AM CDT until September 4 at 1:45AM CDT by NWS Green Bay WI |
| Expires | 2026-09-04T01:45:00-05:00 |
| SenderName | NWS Green Bay WI |
| HasExactCoords | true |
| MergedCount | 4 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.576803487a0ed8cbd87fe58f2ab5445192423229.001.1","noaa_urn:oid:2.49.0.1.840.0.a5621bd38e9c8d9c80b6d5ccdfb6a7e61cba5687.001.1","noaa_urn:oid:2.49.0.1.840.0.b7327e3f01ffeaaf51275a3bf83fc1b7625de8f2.002.1","noaa_urn:oid:2.49.0.1.840.0.b1f97fee27f0dda06c641dd8cbeed88fe26eaa3b.001.1"] |
| Spc ReportType | hail |
| Spc Speed | 175 |
| Spc Location | Mayville |
| Spc County | Dodge |
| Spc State | WI |
| Spc Comments | Relay report from NWSChat. (MKX) |
| Iem TypeSummary | D |
| Iem City | 3 SSW Mayville |
| Iem County | Dodge |
| Iem State | WI |
Safety information
What to do in a thunderstorm
Three things first, then what to do before, during and after. From the US National Weather Service.
For this reportSevere Weather · Fond du Lac
When thunder roars, go indoors
If you can hear thunder, lightning can reach you. Go into a closed building or a hard-topped car with the windows shut.
NWSNowhere is safe outdoors
Not under a tree, not in a tent or a shelter open at the sides. Get away from water and high ground.
NWSWait 30 minutes
Go back out only 30 minutes after the last thunder.
NWS
Before, during, after. Here it is “after”.
Before · When storms are forecast
Check the forecast
Before going out, especially to mountains, the sea or open fields.
Know where to shelter
A closed building or a car you can reach quickly.
National Weather Service
During · While it storms
Keep off water and plumbing
No baths or showers, no washing up.
Away from windows
And from doors and corded phones.
Flash floods
Never drive or walk into a flooded road.
National Weather Service
After · When it has passed
Thirty minutes
After the last thunder, not the last rain.
Fallen lines
Keep away from power lines and anything touching them.
National Weather Service
Questions people ask
Is a car safe in a thunderstorm?
A hard-topped car with the windows closed is: the metal shell carries the current around you. Convertibles, bicycles and motorbikes are not. Source: US National Weather Service.
How long should I wait to go back out?
Thirty minutes after the last thunder you hear. Source: US National Weather Service.
Is it safe under a tree?
No. It is one of the most dangerous places in a storm. Source: US National Weather Service.
Review the area, threshold and delivery channel in your account.