ZIP 50613 Zone 5a
Iowa · USDA zone 5a, average annual extreme minimum -20°F to -15°F.
Nearest qualified station: WATERLOO MUNI AP, IA US (USW00094910), 4.6 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 11 | Earlier date. A last 32°F on or after this day is common. |
| 50% | April 27 | Median. |
| 10% | May 10 | 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 26 | Earlier date. A first 32°F on or before this day is uncommon. |
| 50% | October 10 | Median. |
| 90% | October 21 | 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% | 184 |
| 50% | 165 |
| 90% | 146 |
28°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | May 2 | April 16 | April 3 |
| First, on or before | October 6 | October 20 | October 31 |
| Season at least | 204 days | 185 days | 165 days |
36°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | May 17 | May 6 | April 23 |
| First, on or before | September 16 | September 30 | October 11 |
| Season at least | 166 days | 147 days | 129 days |
Station WATERLOO MUNI AP, IA US (USW00094910). 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 264.6 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.