Power Out Map
– 0% of Merrimack out 0 customers out in New Hampshire

Power outage history

Merrimack County New Hampshire

5.0hours

without power for the average customer in a typical year, 2018–2025

9th most of 10 in New Hampshire 25% below the national median

Worst outage on record Oct 30, 2017 32% of customers out · 90% back in 2.5 days
Hours without power, average customer per year 5.0h / yr State average 6.9 h · national median 6.6 h
Major outages a year 0.9 Peaks over 10% of customers or 50,000 customers
Typical time to restore 90% 25hours Median across major outages, from the peak
Longest single outage 3.6days Oct 30, 2017, over 1% of customers out
Outage hours on storm days 69% Share falling on days with a NOAA storm report here
Worst year 2024 12 hours without power, average customer
Electricity customers 115,899 ORNL customer model · 8 well-covered years

Every day since 2015

Eleven years, one night at a time

Each cell is a day. The brighter it is, the larger the share of Merrimack's customers who were without power at that day's worst moment.

20152016201720182019202020212022202320242025
0%100% of customers out

Year by year

Hours in the dark, per customer

2024 was the worst well-recorded year, at 12 hours for the average customer. Hatched years have a thin record and are left out of the averages.

Merrimack, hours without power per customer

MerrimackUS median countyNew Hampshire average
0 5 10 15 2.0 ’15 3.5 ’16 11 ’17 3.4 ’18 2.8 ’19 5.2 ’20 1.9 ’21 6.6 ’22 5.3 ’23 12 ’24 2.5 ’25 NH 6.9 US 6.6

The record

The biggest outages since 2015

Ranked by customer-hours lost: customers out multiplied by how long they stayed out. Times are local.

Began Storm Peak out Share Lasted 90% restored Customer-hours
Oct 30, 2017 Windstorm 37,350 32% 3.6 d 2.5 d 1.0M
Mar 23, 2024 Winter storm 30,245 26% 2.3 d 40 h 583k
Dec 23, 2022 Flooding 28,015 24% 2.5 d 43 h 517k
Apr 4, 2024 Winter storm 22,459 19% 46 h 35 h 497k
Mar 14, 2023 Winter storm 12,583 11% 2.2 d 24 h 296k
Jul 23, 2016 Thunderstorms 25,159 22% 24 h 18 h 220k
Dec 5, 2020 No storm report 8,559 7% 43 h 32 h 180k
Aug 4, 2020 Hurricane Isaias 10,558 9% 33 h 30 h 166k
Nov 27, 2018 No storm report 9,908 9% 36 h 27 h 126k
Nov 1, 2019 No storm report 12,254 11% 35 h 26 h 112k
Jan 23, 2023 Winter storm 5,651 5% 34 h 22 h 112k
Oct 17, 2019 No storm report 12,030 10% 14 h 12 h 83k

After the peak

How fast the lights come back

Each line is one major outage, from its peak. The amber line is the typical path.

0% 25% 50% 75% 100% peak+24h+48h+72h+96h half back by +10h 90% by +30h

When it happens

The outage clock

Customer-hours out by month (rings, January innermost) and local hour, 2018–2025.

00061218 Jan inside

What was happening

Weather behind the outages

Each outage is matched to NOAA storm reports for Merrimack from twelve hours before it began to its peak. Matching shows coincidence, not proof of cause.

  • Winter storm 45%
  • No storm on record 31%
  • Flooding 15%
  • Thunderstorms 4.7%
  • Tropical storm 4.7%

Who keeps the lights on

Utilities serving Merrimack

As each utility reports to the Energy Information Administration for its whole New Hampshire territory, not this county alone. Outage minutes include major storm days.

Utility Type Outage min / yr Excl. major storms Outages / yr Residential ¢/kWh Customers
Public Service Co of NH Investor Owned 161 83 1.09 24.2 464k
New Hampshire Elec Coop Inc Cooperative 874 526 4.05 24.7 75k
Unitil Energy Systems Investor Owned 98 91 1.36 21.7 69k

EIA Form 861, latest year each utility reported. Outage minutes are SAIDI, the yearly minutes the average customer goes without power; outages a year are SAIFI.

Next door

Neighbouring counties

Across New Hampshire

Where it is darkest

Hours / yr64+

All New Hampshire counties →

About these numbers

Notes

Outages come from the EAGLE-I record of utility outage maps collected every 15 minutes by Oak Ridge National Laboratory. Hours without power are customer-hours divided by the county's 115,899 electricity customers. Averages use well-covered years from 2018. Outages shorter than 15 minutes, and utilities that publish no outage map, are not in the record, so these figures understate the total. How every number is made →