Winter in the Treasure Valley is often a mild affair, but every few decades, Mother Nature reminds us that we live in Idaho. From legendary snowfall that shut down the city to extreme cold that made history, Boise and its neighbors have seen it all.
Here at Totally Boise, we’re digging into the most memorable moments in our region's weather archives and looking ahead to what the upcoming winter might bring.
Historic Highs and Lows: The Treasure Valley Weather Archives
While winter in the valley typically features an average high in the upper 30s and a low in the mid-20s, some days have pushed those limits to truly incredible extremes.
The Coldest Day Ever Recorded
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If you thought last winter was chilly, think again! The all-time record for the coldest temperature in Boise history was a shocking -25°F (-31.7°C). This frigid record was set on December 22, 1990, just days before Christmas, making for a truly unforgettable holiday deep freeze.
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The longest continuous "cold spell" in Boise history, defined as an unbroken series of daily minimum temperatures equal to or below normal, went on for an astounding 41 days, beginning on December 30, 1948.
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Boise also holds a record for the longest stretch of days without hitting 60°F (15.6°C). That streak lasted 157 days during the winter of 2022-2023!
The Snowiest Season and Day in Boise
While our foothills are a snow magnet, the valley floor doesn't often hold snow for long. However, there were some truly epic snow events:
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The greatest single-day snowfall in Boise history was 9.8 inches, which fell on December 20, 1996.
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The snowiest season on record dumped a whopping 50 inches of snow in the winter of 1916-1917.
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In more recent history, many locals remember "Snowmageddon" in 2017, which was part of the 2016-2017 winter that saw a massive seasonal total of 39.1 inches.
Traffic Trouble: Record Cold and Ice Streaks
Icy conditions are arguably the most dangerous part of winter driving.
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One of the most significant winter-related pile-ups in recent memory occurred on I-84 in November 2024 near Mountain Home and Boise, involving an estimated 63 vehicles—including cars, semi-trucks, and a bus. The crash, caused by black ice and compacted snow during a snowstorm, shut down lanes for over eight hours and served as a stark reminder to slow down.
The Upcoming Forecast: What to Expect This Winter (2025–2026)
Ready for a peek into the crystal ball? The long-range outlook for the 2025-2026 winter season suggests a slightly more active season for the Treasure Valley, primarily influenced by a weak La Niña pattern. While some sources forecast temperatures to be warmer than normal overall, we should prepare for the season's coldest periods to arrive sharply in late November, early December, and early February. When it comes to moisture, most models predict Slightly Above Normal precipitation for the region. This trend toward a wetter winter is coupled with forecasts for Above Normal Storm Activity, especially for the northern U.S. and mountain regions, meaning our local ski destinations like Bogus Basin and McCall are favored for impressive snowfall totals. The consensus advises the Treasure Valley to expect a winter that swings between milder spells and potent, moisture-rich cold air outbreaks.
The Takeaway for the Valley: The consensus suggests we should prepare for a wetter winter, meaning more overall moisture. While the valley floor may see slightly warmer temperatures overall, the mountains (and Bogus Basin!) are favored for impressive snowfall totals. Prepare for a season that mixes milder spells with a few potent cold air outbreaks and significant snow events.
Stay safe, drive slow, and enjoy the snow, Boise!