Frost history / Humboldt Wtp, IA
Humboldt Wtp, IA: frost dates by year
Last spring and first fall frost at NOAA station USC00133980, 1997 to 2008, measured from daily minimum temperatures.
Elevation 1,100 ft, 42.720, -94.220. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | Apr 19 | Oct 7 |
| Earliest | Apr 4 (1998) | Sep 30 (2003) |
| Latest | May 5 (2005) | Nov 3 (1998) |
| Trend | 11.5 days later per decade | 1.4 days later per decade |
| Years with data | 11 | 12 |
At 28°F (hard freeze) the median last spring date is Apr 10 and the median first fall date is Oct 23.
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 |
|---|---|---|---|---|
| 2008 | Apr 30 | Oct 17 | Apr 15 | Oct 28 |
| 2007 | Apr 15 | Oct 28 | Apr 13 | Nov 4 |
| 2006 | Apr 9 | Oct 12 | Mar 27 | Oct 12 |
| 2005 | May 5 | Oct 8 | May 3 | Nov 10 |
| 2004 | May 3 | Oct 2 | Apr 14 | Nov 3 |
| 2003 | Apr 10 | Sep 30 | Apr 10 | Oct 2 |
| 2002 | May 1 | Oct 7 | Apr 10 | Oct 13 |
| 2001 | Apr 24 | Oct 6 | Apr 16 | Oct 25 |
| 2000 | Apr 13 | Oct 6 | Apr 9 | Oct 6 |
| 1999 | Apr 19 | Oct 2 | Mar 27 | Oct 4 |
| 1998 | Apr 4 | Nov 3 | Mar 24 | Nov 4 |
| 1997 | no data | Oct 14 | no data | Oct 22 |
"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.