Nassau County Power Outage History
2015–2025 · New York
Average — typical outage frequency and duration nationally. How grades are calculated
Outages by year
Outages by month (seasonality)
Worst outage events on record
| Date | Duration | Customers affected | Cause |
|---|---|---|---|
| Feb 2, 2025 | 0 hrs | 457,901 (90%) | Unnamed event |
| Aug 4, 2020 | 241 hrs | 141,608 (28%) | Tropical Storm Isaias |
| Mar 2, 2018 | 79 hrs | 45,945 (9%) | Coastal Flood |
| Feb 25, 2016 | 50 hrs | 32,589 (6%) | Strong Wind |
| Dec 12, 2023 | 2 hrs | 20,536 (4%) | Unnamed event |
Over the 11 years from 2015 to 2025, Nassau County recorded 4,749 distinct power outage events, averaging 1.6 hours per event.
The single worst outage on record in Nassau County started February 2, 2025, lasting 0 hours and leaving up to 457,901 customers without power (90% of the county) at its peak.
July has historically been the worst month for outages in Nassau County, with 583 events recorded during that month across the dataset.
Based on this history, Nassau County earns a Reliability Grade of C, placing it in the 51st percentile nationally for grid reliability (higher percentile = more reliable).
Sized for Nassau County's outage profile
See more picks in our Best Dual-Fuel Portable Generators for Power Outages roundup.
Champion Power Equipment 4375-Watt Dual Fuel RV Ready Portable Generator with Free 3-Year Warranty
Outage-prep kit
See our outage-prep guides.
Similar counties in New York
Counties with the closest reliability grade and national percentile to Nassau County.
| County | Grade | National percentile |
|---|---|---|
| Jefferson County | C | 51st |
| Wayne County | C | 50th |
| Cayuga County | C | 50th |
| Suffolk County | C | 52nd |
| Rockland County | C | 49th |
FAQ
How often does power go out in Nassau County?
Between 2015 and 2025, Nassau County recorded 4,749 outage events, averaging 1.6 hours each.
What is Nassau County's reliability grade?
Nassau County has a Reliability Grade of C, in the 51st national percentile.
What was the worst power outage in Nassau County?
The worst outage on record started February 2, 2025, lasting 0 hours and affecting up to 457,901 customers.