Frost history / Boulder 14 W, CO
Boulder 14 W, CO: frost dates by year
Last spring and first fall frost at NOAA station USW00094075, 2004 to 2024, measured from daily minimum temperatures.
Elevation 9,828 ft, 40.035, -105.541. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | Jun 21 | Sep 2 |
| Earliest | Jun 2 (2016) | Aug 1 (2023) |
| Latest | Jul 8 (2024) | Sep 20 (2013) |
| Trend | 3.1 days later per decade | 3.1 days later per decade |
| Years with data | 21 | 21 |
At 28°F (hard freeze) the median last spring date is May 26 and the median first fall date is Sep 17.
The trend is a straight-line fit through the years with a freeze. A positive spring trend means the last frost now comes later. Short or patchy records give noisy trends.
Chart
Last spring frost (32°F)
First fall frost (32°F)
Dots are single years. The gray line is the median, the green line the fitted trend.
Year by year
| Year | Last spring 32°F | First fall 32°F | Last spring 28°F | First fall 28°F |
|---|---|---|---|---|
| 2024 | Jul 8 | Sep 6 | May 23 | Oct 8 |
| 2023 | Jun 25 | Aug 1 | May 9 | Sep 25 |
| 2022 | Jun 21 | Sep 10 | Jun 2 | Oct 5 |
| 2021 | Jun 4 | Sep 5 | May 28 | Sep 21 |
| 2020 | Jul 1 | Sep 7 | Jun 9 | Sep 8 |
| 2019 | Jun 23 | Aug 27 | Jun 10 | Sep 13 |
| 2018 | Jul 1 | Aug 20 | May 1 | Sep 21 |
| 2017 | Jul 1 | Sep 5 | May 23 | Sep 17 |
| 2016 | Jun 2 | Sep 9 | May 26 | Sep 9 |
| 2015 | Jun 8 | Aug 19 | May 25 | Sep 19 |
| 2014 | Jun 15 | Sep 11 | May 15 | Sep 11 |
| 2013 | Jun 6 | Sep 20 | Jun 4 | Sep 20 |
| 2012 | Jun 13 | Aug 19 | May 29 | Oct 3 |
| 2011 | Jun 20 | Sep 3 | May 26 | Sep 21 |
| 2010 | Jun 14 | Sep 2 | May 31 | Sep 3 |
| 2009 | Jun 22 | Aug 9 | May 17 | Sep 19 |
| 2008 | Jun 29 | Aug 15 | May 30 | Sep 4 |
| 2007 | Jun 14 | Sep 10 | Jun 8 | Sep 11 |
| 2006 | Jun 27 | Aug 28 | May 16 | Sep 3 |
| 2005 | Jun 13 | Aug 31 | May 14 | Sep 14 |
| 2004 | Jun 23 | Aug 12 | Jun 22 | Aug 28 |
"none" means the station recorded no freeze at that threshold in that half of the year. "no data" means more than 10% of the season's daily readings were missing. Years with no usable data are left out. See the methodology for the rules, and the ZIP lookup for 1991 to 2020 frost probabilities.