O'Brien County, Iowa · Frost dates
O'Brien County frost dates.
First-frost, last-frost, and growing-season length for O'Brien County, Iowa. Sourced from NOAA 1991-2020 Climate Normals.
Data confidence: high · USDA zone: 5a
32°F — light freeze
Last spring frost
- 10%
- 05-11
- 20%
- 05-06
- 50%
- 04-29
- 80%
- 04-18
- 90%
- 04-13
First fall frost
- 10%
- 09-26
- 20%
- 10-01
- 50%
- 10-10
- 80%
- 10-19
- 90%
- 10-23
28°F — killing freeze
Last spring freeze
- 10%
- 05-01
- 20%
- 04-28
- 50%
- 04-18
- 80%
- 04-08
- 90%
- 04-03
First fall freeze
- 10%
- 10-05
- 20%
- 10-10
- 50%
- 10-21
- 80%
- 10-30
- 90%
- 11-04
Growing season length (days, 28°F threshold)
- Short year
- 157
- Median
- 186
- Long year
- 215
Source NOAA station
PRIMGHAR, IA US
0.3 mi · 30 yrs of record (1991–2020) · 1520 ft elev.
Data from PRIMGHAR, IA US, 0.3 miles away with 30-year NOAA record (1991-2020).
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