ZIP 55903 Zone 4b

Minnesota · USDA zone 4b, average annual extreme minimum -25°F to -20°F.

Nearest qualified station: ROCHESTER INTL AP, MN US (USW00014925), 8.7 miles from the Census ZCTA internal point for this ZIP.

Median last 32°F is April 30. Median first 32°F is October 6. The 50% growing-season length is 159 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 15Earlier date. A last 32°F on or after this day is common.
50%April 30Median.
10%May 13Later 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%September 22Earlier date. A first 32°F on or before this day is uncommon.
50%October 6Median.
90%October 20Later 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%178
50%159
90%140

28°F threshold

10%50%90%
Last, on or afterMay 2April 18April 4
First, on or beforeOctober 4October 17October 31
Season at least201 days180 days161 days

36°F threshold

10%50%90%
Last, on or afterMay 21May 9April 28
First, on or beforeSeptember 14September 28October 11
Season at least158 days140 days122 days

Station ROCHESTER INTL AP, MN US (USW00014925). Completeness flag S, 30 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 397.5 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

Methodology · Minnesota cities