Johnson County, Iowa · Frost dates
Johnson County frost dates.
First-frost, last-frost, and growing-season length for Johnson County, Iowa. Sourced from NOAA 1991-2020 Climate Normals.
Data confidence: high · USDA zone: 5a
32°F — light freeze
Last spring frost
- 10%
- 05-06
- 20%
- 05-01
- 50%
- 04-21
- 80%
- 04-10
- 90%
- 04-05
First fall frost
- 10%
- 10-04
- 20%
- 10-10
- 50%
- 10-18
- 80%
- 10-26
- 90%
- 10-31
28°F — killing freeze
Last spring freeze
- 10%
- 04-27
- 20%
- 04-21
- 50%
- 04-09
- 80%
- 03-31
- 90%
- 03-25
First fall freeze
- 10%
- 10-15
- 20%
- 10-19
- 50%
- 10-28
- 80%
- 11-04
- 90%
- 11-09
Growing season length (days, 28°F threshold)
- Short year
- 171
- Median
- 202
- Long year
- 229
Source NOAA station
IOWA CITY MUNI AP, IA US
3.6 mi · 30 yrs of record (1991–2020) · 650 ft elev.
Data from IOWA CITY MUNI AP, IA US, 3.6 miles away with 30-year NOAA record (1991-2020).
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