Nassau CountyPower Outage History
What this grade means
Average — typical outage frequency and duration nationally. This county sits in the middle of the national distribution — its outage frequency and duration over the past 12 years are close to the nationwide median, neither notably better nor worse than most other US counties. A typical amount of backup-power preparedness is reasonable here.
Outages by year
Outages by month (seasonality)
Worst outage events on record
| Date | Duration | Customers affected | Cause |
|---|---|---|---|
| Feb 2, 2025 | <1 hr | 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 |
Was There an Outage on a Specific Date?
Pick a date to see whether a power outage was recorded for Nassau County, New York that day.
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 less than 1 hour 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).
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 |
Most reliable counties nationally
The top 3 counties nationally by reliability grade and percentile.
| County | State | Grade | National percentile |
|---|---|---|---|
| Clay County | South Dakota | A | 100th |
| Clearwater County | Minnesota | A | 99th |
| Limestone County | Alabama | A | 99th |
Least reliable counties nationally
The bottom 3 counties nationally by reliability grade and percentile.
| County | State | Grade | National percentile |
|---|---|---|---|
| Clay County | West Virginia | F | 0th |
| Lincoln County | West Virginia | F | 0th |
| Cameron Parish | Louisiana | F | 0th |
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 less than 1 hour and affecting up to 457,901 customers.