88
Recorded events
7
Direct deaths
100
Direct injuries
$489.2M
Property damage
Flash Flood in Somerset County, New Jersey: 88 recorded events between 1996 and 2025. The strongest on record measured 0. That places the county #224 nationally and #9 statewide for this hazard.
Decade by decade
Flash Flood in Somerset County, New Jersey: events per decade
Reporting practice changed over time — early decades are undercounted, not calmer.
The busiest decade for flash flood in Somerset County is the 2010s, when 30 of the county's 88 recorded events were logged. Comparing decades is useful for spotting active periods, but the earliest years are thin because systematic reporting for this hazard began later.
Within the Somerset County archive, flash flood makes up 14.2% of all recorded severe weather across 8 hazard types. Nationally the county sits at #224 for this hazard and #9 within New Jersey, putting it in the 92.7 percentile of all U.S. counties.
Seasonality
Events by month
Jul is the peak month for flash flood in Somerset County with 31 recorded events, while Jan is the quietest. Seasonality here is a property of the archive as much as the climate: reports cluster where population and spotter networks are densest.
Significant events
Deadliest on record
| Date | Location | Scale | Deaths | Injuries | Damage |
|---|---|---|---|---|---|
| Sep 1, 2021 | BRANCHBURG PARK | 0 | 3 | 0 | $25.0M |
| Sep 16, 1999 | COUNTYWIDE | 0 | 2 | 100 | $358.0M |
| Sep 1, 2021 | BRANCHBURG PARK | 0 | 2 | 0 | $75.0M |
Most recent
Latest recorded events
| Date | Location | Magnitude | Damage |
|---|---|---|---|
| Jul 31, 2025 | GREEN BROOK | 0 | $0 |
| Jul 31, 2025 | PLUCKEMIN | 0 | $0 |
| Jul 15, 2025 | MANVILLE | 0 | $15K |
| Jul 14, 2025 | BOUND BROOK | 0 | $0 |
| Jul 14, 2025 | GREEN BROOK | 0 | $30K |
| Jul 14, 2025 | BOUND BROOK | 0 | $0 |
| Jul 14, 2025 | WATCHUNG | 0 | $0 |
| Jul 14, 2025 | GREEN BROOK | 0 | $0 |
| Jul 14, 2025 | WATCHUNG | 0 | $0 |
| May 14, 2025 | GREEN BROOK | 0 | $0 |
Other hazards here
More from Somerset County
- Thunderstorm Wind 323
- Flood 88
- Hail 43
From the record
What the reports say
Written by National Weather Service staff at the time of the event · public domain
Widespread flash flooding occurred in the northern half of Somerset County with numerous roads closures. There were three flood related fatalities in northern Somerset County, all in Bridgewater Township. There were approximately 1200 water rescues in the entire county. Many buildings and homes were either damaged or destroyed by the flood waters. Most waterways in the county overflowed their banks, including the Raritan River, the Millstone River, Green Brook, Stony Brook and Middle Brook.
Widespread flash flooding occurred in the southern half of Somerset County with numerous road closures. There were two flood related fatalities in southern Somerset County, both in Hillsborough Township. There were approximately 1200 water rescues in the entire county. Many buildings and homes were either damaged or destroyed by the flood waters. Most waterways in the county overflowed their banks, including the Raritan River, the Millstone River, Green Brook, Stony Brook and Middle Brook.
Thunderstorms with torrential downpours caused flash flooding of roadways and streams in northwestern Somerset County and hit Bedminister, Peapack-Gladstone and Bernardsville the hardest. The flash flooding affected New Jersey Commuter Rail Service. Eastbound commuter rail service along the Morris and Essex Line was suspended for the day after flash flooding caused four to six washouts of stone supports along the Gladstone Branch tracks. Westbound service continued, but delays averaged 45 minutes. Substitute eastbound bus service was provided. About ten people in Peapack-Gladstone self evacuated to the Municipal Building. The runoff from the heavy rain and also caused flooding along the Lamington River and Middle Brook. Event precipitation totals included 5.85 inches in Peapack-Gladstone, 5.14 inches in Pottersville, 4.94 inches in Far Hills and 3.99 inches in Middlebush.
Quick answers
Frequently asked
How many flash flood events are on record in Somerset County, New Jersey?
88 flash flood events are recorded in Somerset County between 1996 and 2025, causing 7 direct deaths.
What is the strongest flash flood recorded in Somerset County?
The strongest flash flood on record in Somerset County measured 0.
Where does the flash flood data for Somerset County come from?
All events come from the NOAA/NCEI Storm Events Database, the federal public-domain archive of severe weather reports. Dates are UTC, damage is as reported and not inflation-adjusted, and the most recent entries may still be revised.
Cite this page
“Flash Flood in Somerset County, New Jersey.” Severe Weather History. severeweatherhistory.com/county/new-jersey/somerset-county/flash-flood/ · Data: NOAA/NCEI, FEMA, U.S. Census — public domain.