ZIP 55806 Zone 4b
Minnesota · USDA zone 4b, average annual extreme minimum -25°F to -20°F.
Nearest qualified station: DULUTH HARBOR STN, MN US (USC00212246), 1.8 miles from the Census ZCTA internal point for this ZIP.
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.
| Probability | Date | How to read it |
|---|---|---|
| 90% | April 24 | Earlier date. A last 32°F on or after this day is common. |
| 50% | May 14 | Median. |
| 10% | June 1 | Later 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.
| Probability | Date | How to read it |
|---|---|---|
| 10% | September 25 | Earlier date. A first 32°F on or before this day is uncommon. |
| 50% | October 12 | Median. |
| 90% | October 26 | Later 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 long | Days |
|---|---|
| 10% | 175 |
| 50% | 149 |
| 90% | 124 |
28°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | May 18 | April 29 | April 11 |
| First, on or before | October 9 | October 25 | November 7 |
| Season at least | 199 days | 179 days | 154 days |
36°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | June 16 | May 31 | May 12 |
| First, on or before | September 12 | September 30 | October 14 |
| Season at least | 145 days | 121 days | 98 days |
Station DULUTH HARBOR STN, MN US (USC00212246). Completeness flag R, 14 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 185.9 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.