Tanana River · Nenana, Alaska · 64.56°N
Nenana Ice Classic
Since 1917, Alaskans have bet on the exact moment ice on the Tanana River breaks at Nenana. A wooden tripod planted on the frozen river is wired to a clock on shore. When the ice moves, the cable trips the clock and stamps a date and time. 110 years of breakup dates and 479 pre-breakup ice thickness measurements across 38 years.
Breakup dates · 1917–2026
The day of year the tripod fell each spring. Trend line shows a 9-year centered moving average. Five recent years have winning times (UTC−9, AKST/AKDT) where reported.
Ice thickness · pre-breakup measurements
Tanana River ice thickness measured weekly through winter and spring, layered by year from Jan through breakup. Recent years are highlighted; older years fade back into the background. Scrub or hover to inspect a year.
Recent winning times
| Year | Date | Time (AKST) | Day of year | Ice measurements |
|---|---|---|---|---|
| 2026 | May 4 | 6:58 PM | 124 | 8 obs |
| 2025 | Apr 27 | 3:56 PM | 117 | 6 obs |
| 2024 | Apr 27 | 5:18 AM | 118 | 8 obs |
| 2023 | May 8 | · | 128 | 15 obs |
| 2022 | May 2 | · | 122 | 15 obs |
| 2021 | Apr 30 | · | 120 | 15 obs |
| 2020 | Apr 27 | 12:56 PM | 118 | 12 obs |
| 2019 | Apr 14 | 12:21 AM | 104 | 9 obs |
| 2018 | May 1 | · | 121 | 11 obs |
| 2017 | May 1 | · | 121 | 14 obs |
| 2016 | Apr 23 | · | 114 | 14 obs |
| 2015 | Apr 24 | · | 114 | 11 obs |
| 2014 | Apr 25 | · | 115 | 8 obs |
| 2013 | May 20 | · | 140 | 22 obs |
| 2012 | Apr 23 | · | 114 | 14 obs |
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