New Hampshire has no state ice-out dataset. What it has instead is one of the most closely watched single dates in New England: ice-out on Lake Winnipesaukee, called from an aircraft, in an unbroken line since 1887.
Dates from past winters. For today’s ice, ask the agency that manages the water.
The Winnipesaukee ice-out call is made by a pilot flying the lake, and the running list of dates is published by the community site winnipesaukee.com. It is not a government dataset. For 1887 through 2008 the same dates appear in the public domain USGS report this page is built on.
40 of 40 of the most recent recorded years had already seen ice out on Sunapee Lake by this date.
The median across the whole record is April 24, which is 168 days ago on this year’s calendar. The record itself runs to 2019, so this is a comparison against history and not a statement about the current season.
This counts recorded years, not this year; the current season comes from the agency linked above.
Ordered by how much record there is behind them. The median is across every recorded year; the second figure is across the most recent 30 recorded years, which is the fairer thing to compare against a lake you know today.
Names are reproduced exactly as the source database records them, which is often a shortened form: a lake filed as “Detroit” or “George” is Detroit Lake or Lake George to everyone who lives on it. The names stay as recorded, because United States lakes split unpredictably between “Lake X” and “X Lake”.
Lake in New Hampshire · 151 recorded years, 1869 to 2019
Across the whole record, ice out has moved 9 days earlier per century across the record.
Mean date per decade. Only decades with four or more observations are shown, and the scale starts near the shortest bar rather than at January 1, so small differences stay visible.
Lake in New Hampshire · 133 recorded years, 1887 to 2019
Across the whole record, ice out has moved 5 days earlier per century across the record.
Mean date per decade. Only decades with four or more observations are shown, and the scale starts near the shortest bar rather than at January 1, so small differences stay visible.
Lake in New Hampshire · 119 recorded years, 1880 to 2016
Across the whole record, ice out has moved 7 days earlier per century across the record.
Mean date per decade. Only decades with four or more observations are shown, and the scale starts near the shortest bar rather than at January 1, so small differences stay visible.
Lake in New Hampshire · 89 recorded years, 1920 to 2008record ends 2008
Across the whole record, ice out has moved barely at all across the record.
Mean date per decade. Only decades with four or more observations are shown, and the scale starts near the shortest bar rather than at January 1, so small differences stay visible.
| Lake | Record | Median ice out | Last 30 years | Earliest | Latest | Change per century |
|---|---|---|---|---|---|---|
| Sunapee Lake | 1869 to 2019 (151) | Apr 24 | Apr 20 | Mar 19 2016 | May 15 1888 | -9 days |
| Lake Winnipesaukee | 1887 to 2019 (133) | Apr 20 | Apr 20 | Mar 19 2016 | May 13 1888 | -5.3 days |
| Umbagog Lake | 1880 to 2016 (119) | May 1 | Apr 29 | Apr 10 1910 | May 24 1888 | -6.6 days |
| First Connecticut Lake | 1920 to 2008 (89) | May 5 | May 3 | Apr 9 1921 | May 20 1972 | +1.5 days |
Dates are day of year, rendered on a common non leap calendar so the same stored value always reads the same way. “Change per century” is a least squares line through the observations, shown only where a record spans 80 years or more; a century figure extrapolated from a 40 year window describes the decades that happened to be sampled rather than the lake. Where a record ends before 2010 the card says so; a great many of these series stopped when a particular person stopped keeping them.
Of the 4 New Hampshire lakes with a record long enough to state a century trend, 3 show ice out moving earlier. The median shift across those lakes is -5.3 days per century. That is a description of a line fitted to observations, not a forecast, and any single lake can and does swing three or four weeks between consecutive years.
The call comes from the air. A pilot at Emerson Aviation in Gilford flies the lake several times a day through the spring, and when the pilot makes the call it is treated as official. The lineage runs from shore observers to Bob Aldrich, who called it for around fifty years, to Alan and then Dave Emerson.
Squam draws its own line. Squam Lake next door uses a different test entirely: ice-out is when you can drive a boat from the covered bridge in Ashland to the Sandwich town beach. The Squam Lakes Association has kept that record since 1978.
Benson, B., Magnuson, J. and Sharma, S. (2000). Global Lake and River Ice Phenology Database. (G01377, Version 1). Boulder, Colorado USA. National Snow and Ice Data Center. https://doi.org/10.7265/N5W66HP8 Accessed 2026-08-24.
Which is worth knowing, because it means those series can be checked against a federal document rather than taken on trust. It also carries the observer names for every lake, which is the part of this record that is really a social history.
Hodgkins, G.A., 2010, Historical ice-out dates for 29 lakes in New England, 1807 to 2008: U.S. Geological Survey Open-File Report 2010-1214, 32 p. https://pubs.usgs.gov/of/2010/1214/
The Winnipesaukee list was assembled in 1974 by Dr. William K. Widgert, who pulled together the dates already on record back to 1887; the years since have been added one at a time.
Ice out and ice in dates are historical observations compiled by the National Snow and Ice Data Center and, for the New England lakes, by the U.S. Geological Survey. They describe past years only, and a past year says nothing about the ice on a lake today. For current ice and for anything involving going out on it, contact New Hampshire Fish and Game. National picture: every state with a lake ice record →
Hero image: “Lake Winnipesaukee (54048636120)” by Accidental Nomad from Between States, USA, CC BY 2.0