Upper Saranac Lake officially froze over on December 7, marking an earlier-than-average start to winter for the 2025–26 season. Ice-in is recorded when the lake’s surface becomes fully covered in ice. While this year’s freeze-up arrived on the early side, long-term trends across the Adirondacks tell a different story: lakes are freezing significantly later now than they did a century ago.
The Upper Saranac Foundation (USF) maintains ice-out records back to 1998, but ice-in tracking only began in 2012. Since then, the earliest documented ice-in was November 29, 2013, and the latest was January 9, 2023.
To better understand long-term patterns, USF looks to nearby Mirror Lake in Lake Placid, which holds one of the most complete ice records in the state, extending back to 1903. The data shows:
- Mirror Lake now freezes an average of 17 days later than it did in 1903.
- The duration of ice cover has shortened by an average of 24 days since record-keeping began.
- Mirror Lake’s historic average ice-cover duration is 140 days; since 2000, that average has fallen to 124 days.
These trends reflect broader changes observed across North America. Shorter and later ice seasons are linked to warming lake temperatures, which can:
- Threaten cold-water fish species such as lake trout,
- Increase vulnerability to non-native and invasive species, and
- Alter seasonal lake stratification and habitat conditions.
Long-term monitoring provides essential insight into how local ecosystems are responding to climate change.
To explore USF’s ice-in and ice-out records, visit: https://usfoundation.net/programs/ice-in-ice-out/