ZIP 52806 Zone 5b

Iowa · USDA zone 5b, average annual extreme minimum -15°F to -10°F.

Nearest qualified station: DAVENPORT, IA US (USW00094982), 2.8 miles from the Census ZCTA internal point for this ZIP.

Median last 32°F is April 23. Median first 32°F is October 15. The 50% growing-season length is 174 days. The green band runs from the median last frost to the median first frost. Thin ticks mark the 10%, 50%, and 90% dates.

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Last 32°F in spring

NCEI’s probability is the chance the last spring minimum of 32°F or lower occurs on or after the date.

ProbabilityDateHow to read it
90%April 8Earlier date. A last 32°F on or after this day is common.
50%April 23Median.
10%May 8Later date. A last 32°F on or after this day is uncommon.

First 32°F in fall

NCEI’s probability is the chance the first autumn minimum of 32°F or lower occurs on or before the date.

ProbabilityDateHow to read it
10%October 1Earlier date. A first 32°F on or before this day is uncommon.
50%October 15Median.
90%October 28Later date. A first 32°F on or before this day is common.

32°F growing-season length

Days between the last spring 32°F and the first autumn 32°F. The figure is a length the season meets or exceeds at that probability, from NCEI, not a subtraction done on this site.

Probability the season is at least this longDays
10%193
50%174
90%153

28°F threshold

10%50%90%
Last, on or afterApril 30April 12March 29
First, on or beforeOctober 11October 24November 5
Season at least214 days193 days173 days

36°F threshold

10%50%90%
Last, on or afterMay 17May 2April 17
First, on or beforeSeptember 19October 4October 17
Season at least173 days154 days135 days

Station DAVENPORT, IA US (USW00094982). Completeness flag S, 24 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 100%. Freeze dates are conditional on that threshold occurring. Elevation 229.8 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

Methodology · Iowa cities