ZIP 60431 Zone 5b
Illinois · USDA zone 5b, average annual extreme minimum -15°F to -10°F.
Nearest qualified station: JOLIET BRANDON RD DAM, IL US (USC00114530), 4.5 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 3 | Earlier date. A last 32°F on or after this day is common. |
| 50% | April 19 | Median. |
| 10% | May 7 | 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 12 | Earlier date. A first 32°F on or before this day is uncommon. |
| 50% | October 25 | Median. |
| 90% | November 6 | 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% | 208 |
| 50% | 188 |
| 90% | 167 |
28°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | April 21 | April 5 | March 22 |
| First, on or before | October 23 | November 4 | November 21 |
| Season at least | 231 days | 211 days | 191 days |
36°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | May 18 | May 1 | April 16 |
| First, on or before | October 2 | October 15 | October 27 |
| Season at least | 185 days | 166 days | 147 days |
Station JOLIET BRANDON RD DAM, IL US (USC00114530). 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 165.5 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.