ZIP 60446 Zone 6a
Illinois · USDA zone 6a, average annual extreme minimum -10°F to -5°F.
Nearest qualified station: ROMEOVILLE WFO, IL US (USC00117457), 2.1 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 7 | Earlier date. A last 32°F on or after this day is common. |
| 50% | April 20 | Median. |
| 10% | May 6 | 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 7 | Earlier date. A first 32°F on or before this day is uncommon. |
| 50% | October 22 | Median. |
| 90% | November 3 | 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% | 202 |
| 50% | 184 |
| 90% | 162 |
28°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | April 23 | April 8 | March 27 |
| First, on or before | October 19 | November 1 | November 15 |
| Season at least | 226 days | 206 days | 186 days |
36°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | May 17 | May 1 | April 17 |
| First, on or before | September 28 | October 12 | October 24 |
| Season at least | 180 days | 162 days | 142 days |
Station ROMEOVILLE WFO, IL US (USC00117457). Completeness flag R, 23 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 201.2 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.