Last spring frost
Apr 26
Frost Dates for Gilbert, IA
First fall frost
Oct 8
Growing season
164 days
Hardiness zone
5b
In an average year around Gilbert, IA, the last spring frost (32°F) is about Apr 26 and the first fall frost is about Oct 8, giving roughly a 164-day growing season. To be safe most years, wait until Apr 11 before setting out tender plants.
Last spring frost
Dates the last frost of spring typically ends. Plant tender crops after the risk has passed for your comfort level.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | May 17 | May 5 | Apr 21 |
| Freeze (32°F) | May 9 | Apr 26 | Apr 11 |
| Hard (28°F) | May 1 | Apr 14 | Apr 1 |
| Severe (24°F) | Apr 21 | Apr 4 | Mar 17 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 17 | May 13 | May 10 | May 7 | May 5 | May 3 | May 1 | Apr 27 | Apr 21 |
| 32°F | May 9 | May 5 | May 2 | Apr 29 | Apr 26 | Apr 22 | Apr 19 | Apr 15 | Apr 11 |
| 28°F | May 1 | Apr 25 | Apr 21 | Apr 17 | Apr 14 | Apr 11 | Apr 8 | Apr 5 | Apr 1 |
| 24°F | Apr 21 | Apr 15 | Apr 10 | Apr 7 | Apr 4 | Apr 2 | Mar 30 | Mar 25 | Mar 17 |
| 20°F | Apr 13 | Apr 6 | Apr 2 | Mar 30 | Mar 26 | Mar 21 | Mar 17 | Mar 13 | Mar 7 |
| 16°F | Apr 2 | Mar 28 | Mar 22 | Mar 18 | Mar 15 | Mar 11 | Mar 8 | Mar 5 | Mar 1 |
First fall frost
Dates the first frost of fall typically arrives. Count back by a crop's days-to-maturity to know your planting cutoff.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Sep 15 | Sep 28 | Oct 11 |
| Freeze (32°F) | Sep 23 | Oct 8 | Oct 21 |
| Hard (28°F) | Oct 4 | Oct 19 | Oct 31 |
| Severe (24°F) | Oct 16 | Oct 29 | Nov 10 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 15 | Sep 19 | Sep 22 | Sep 26 | Sep 28 | Oct 1 | Oct 4 | Oct 7 | Oct 11 |
| 32°F | Sep 23 | Sep 28 | Oct 2 | Oct 5 | Oct 8 | Oct 11 | Oct 14 | Oct 17 | Oct 21 |
| 28°F | Oct 4 | Oct 10 | Oct 14 | Oct 16 | Oct 19 | Oct 21 | Oct 23 | Oct 26 | Oct 31 |
| 24°F | Oct 16 | Oct 20 | Oct 23 | Oct 26 | Oct 29 | Oct 31 | Nov 2 | Nov 5 | Nov 10 |
| 20°F | Oct 24 | Oct 30 | Nov 1 | Nov 4 | Nov 6 | Nov 8 | Nov 12 | Nov 16 | Nov 21 |
| 16°F | Nov 2 | Nov 6 | Nov 9 | Nov 12 | Nov 15 | Nov 19 | Nov 23 | Nov 27 | Dec 2 |
Growing season is measured at 32°F with about 50% probability. Hardiness zone from the 2023 USDA map; frost normals from NOAA 1991-2020.
Where this data comes from
@endif These dates are computed from the nearest official weather station with long-term records: Ames Muni Ap, Ia, about 8.7 miles away@if(!empty($station['elevation_ft'])), at 930 ft elevation. The further the station and the greater the elevation difference from your yard, the more your local frost timing can vary.
How we calculate these dates
Frost and freeze dates come from the NOAA 1991–2020 U.S. Climate Normals, the National Oceanic and Atmospheric Administration's 30-year averages for each weather station. A date shown at the 50% level is the median: in half of years the frost falls on or before it. The 10% and 90% columns show the early and late ends of the range, so you can plant on the odds you're comfortable with. These are long-term averages, not a forecast for this year - always check your local outlook before planting.
Source: NOAA National Centers for Environmental Information, 1991–2020 Climate Normals (public domain). Harman is not affiliated with or endorsed by NOAA.
Frequently asked questions
When is the last frost in Gilbert, IA?
On average, the last spring frost (32°F) around Gilbert, IA is about Apr 26. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 11.
When is the first frost in the fall?
The first fall frost around Gilbert, IA typically arrives about Oct 8. Count back by a crop's days to maturity to find the latest date you can plant it.
When can I plant tomatoes and other tender crops?
Tender crops like tomatoes, peppers and basil are damaged by frost, so wait until the last spring frost has passed - around Apr 26 on average, or Apr 11 to be safe most years.
How long is the growing season here?
The frost-free growing season (between the last spring and first fall 32°F frost) is about 164 days in a typical year.
Are these dates a forecast for this year?
No. They are 30-year averages from the NOAA 1991–2020 Climate Normals, not a prediction for the current year. Use them for planning and always check your local weather forecast before planting or protecting crops.
Local weather for 50105 Planting calendar → Iowa frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026