ZIP 61104 Zone 5b
Illinois · USDA zone 5b, average annual extreme minimum -15°F to -10°F.
Nearest qualified station: ROCKFORD GTR ROCKFORD AP, IL US (USW00094822), 4.1 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 10 | Earlier date. A last 32°F on or after this day is common. |
| 50% | April 24 | Median. |
| 10% | May 8 | 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% | October 2 | Earlier date. A first 32°F on or before this day is uncommon. |
| 50% | October 17 | Median. |
| 90% | October 30 | 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% | 192 |
| 50% | 174 |
| 90% | 154 |
28°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | April 27 | April 13 | March 31 |
| First, on or before | October 14 | October 28 | November 10 |
| Season at least | 217 days | 197 days | 177 days |
36°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | May 19 | May 4 | April 21 |
| First, on or before | September 23 | October 6 | October 20 |
| Season at least | 173 days | 153 days | 134 days |
Station ROCKFORD GTR ROCKFORD AP, IL US (USW00094822). 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 222.5 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.