Union County, Iowa · Frost dates
Union County frost dates.
First-frost, last-frost, and growing-season length for Union County, Iowa. Sourced from NOAA 1991-2020 Climate Normals.
Data confidence: high · USDA zone: 5a
32°F — light freeze
Last spring frost
- 10%
- 05-09
- 20%
- 05-06
- 50%
- 04-28
- 80%
- 04-18
- 90%
- 04-14
First fall frost
- 10%
- 09-24
- 20%
- 09-30
- 50%
- 10-11
- 80%
- 10-21
- 90%
- 10-26
28°F — killing freeze
Last spring freeze
- 10%
- 05-02
- 20%
- 04-28
- 50%
- 04-17
- 80%
- 04-08
- 90%
- 04-05
First fall freeze
- 10%
- 10-05
- 20%
- 10-12
- 50%
- 10-23
- 80%
- 10-31
- 90%
- 11-04
Growing season length (days, 28°F threshold)
- Short year
- 156
- Median
- 189
- Long year
- 213
Source NOAA station
CRESTON 2 SW, IA US
7.8 mi · 30 yrs of record (1991–2020) · 1296 ft elev.
Data from CRESTON 2 SW, IA US, 7.8 miles away with 30-year NOAA record (1991-2020).
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