| Quick facts | Answer |
|---|---|
| Station | Boise Air Terminal |
| Period | winter 2000-01 - 2026-10-16 |
| Average nights ≤ 20°F per winter | 21.3 |
| Most in one winter | 44 nights (2016-17) |
| Last winter (2025-26) | 5 nights |
| Peak month | Dec |
Nights at or below 20°F, winter by winter
| Winter | Nights ≤ 20°F | Coldest low | Note |
|---|---|---|---|
| 2026-27 | 0 | 37°F | partial (108 days of data) |
| 2025-26 | 5 | 15°F | |
| 2024-25 | 18 | 5°F | |
| 2023-24 | 12 | 3°F | |
| 2022-23 | 29 | 6°F | |
| 2021-22 | 25 | -3°F | |
| 2020-21 | 11 | 14°F | |
| 2019-20 | 10 | 16°F | |
| 2018-19 | 17 | 10°F | |
| 2017-18 | 22 | 8°F | |
| 2016-17 | 44 | -11°F | |
| 2015-16 | 20 | 4°F | |
| 2014-15 | 16 | 1°F | |
| 2013-14 | 30 | -7°F | |
| 2012-13 | 31 | -3°F | |
| 2011-12 | 29 | 11°F | |
| 2010-11 | 24 | 7°F | |
| 2009-10 | 17 | -6°F | |
| 2008-09 | 18 | 7°F | |
| 2007-08 | 25 | 5°F | |
| 2006-07 | 32 | 7°F | |
| 2005-06 | 23 | 7°F | |
| 2004-05 | 14 | 16°F | |
| 2003-04 | 18 | 1°F | |
| 2002-03 | 5 | 13°F | |
| 2001-02 | 31 | 12°F | |
| 2000-01 | 29 | 7°F |
Which months bring the hard freezes
Average nights at or below 20°F per month:
| Month | Avg nights |
|---|---|
| Oct | 0.2 |
| Nov | 2.0 |
| Dec | 8.2 |
| Jan | 7.5 |
| Feb | 3.2 |
| Mar | 0.3 |
What it means for mobile mechanic in Boise
A cold battery has far less cranking power, so hard-freeze nights are when weak batteries fail to start.
How we counted
We downloaded NOAA's daily record for station USW00024131 and counted every night whose official low (TMIN) was 20°F or colder. A winter runs July to June. Winters with fewer than 330 days of data are marked partial and left out of the average.
Use this data
Reporters, bloggers and neighborhood groups are welcome to use these numbers. Please cite NOAA and link to this page. We refresh it from NOAA's files regularly.
