St. Mary's County Power Outage History
2014–2025 · Maryland
Top 20% most reliable nationally — infrequent, short outages. How grades are calculated
Outages by year
Outages by month (seasonality)
Worst outage events on record
| Date | Duration | Customers affected | Cause |
|---|---|---|---|
| Sep 22, 2015 | 1 hrs | 20,346 (18%) | Unnamed event |
| Jan 3, 2022 | 63 hrs | 14,054 (13%) | Winter Storm |
| Feb 29, 2024 | 2 hrs | 12,061 (11%) | Unnamed event |
| Mar 2, 2018 | 56 hrs | 11,852 (11%) | Dense Fog |
| May 16, 2025 | 24 hrs | 11,745 (11%) | Thunderstorm Wind |
Over the 12 years from 2014 to 2025, St. Mary's County recorded 765 distinct power outage events, averaging 2.1 hours per event.
The single worst outage on record in St. Mary's County started September 22, 2015, lasting 1 hours and leaving up to 20,346 customers without power (18% of the county) at its peak.
August has historically been the worst month for outages in St. Mary's County, with 89 events recorded during that month across the dataset.
Based on this history, St. Mary's County earns a Reliability Grade of A, placing it in the 81st percentile nationally for grid reliability (higher percentile = more reliable).
Sized for St. Mary's County's outage profile
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Similar counties in Maryland
Counties with the closest reliability grade and national percentile to St. Mary's County.
| County | Grade | National percentile |
|---|---|---|
| Charles County | A | 80th |
| Queen Anne's County | B | 79th |
| Caroline County | B | 79th |
| Dorchester County | A | 83rd |
| Howard County | B | 78th |
FAQ
How often does power go out in St. Mary's County?
Between 2014 and 2025, St. Mary's County recorded 765 outage events, averaging 2.1 hours each.
What is St. Mary's County's reliability grade?
St. Mary's County has a Reliability Grade of A, in the 81st national percentile.
What was the worst power outage in St. Mary's County?
The worst outage on record started September 22, 2015, lasting 1 hours and affecting up to 20,346 customers.