Last spring frost
Apr 8
Frost Dates for Mediapolis, IA
First fall frost
Oct 29
Growing season
202 days
Hardiness zone
5b
In an average year around Mediapolis, IA, the last spring frost (32°F) is about Apr 8 and the first fall frost is about Oct 29, giving roughly a 202-day growing season. To be safe most years, wait until Mar 26 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 5 | Apr 20 | Apr 6 |
| Freeze (32°F) | Apr 23 | Apr 8 | Mar 26 |
| Hard (28°F) | Apr 13 | Mar 31 | Mar 14 |
| Severe (24°F) | Apr 5 | Mar 20 | Mar 5 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 5 | Apr 30 | Apr 26 | Apr 22 | Apr 20 | Apr 17 | Apr 14 | Apr 10 | Apr 6 |
| 32°F | Apr 23 | Apr 18 | Apr 14 | Apr 11 | Apr 8 | Apr 6 | Apr 3 | Apr 1 | Mar 26 |
| 28°F | Apr 13 | Apr 8 | Apr 5 | Apr 2 | Mar 31 | Mar 29 | Mar 24 | Mar 20 | Mar 14 |
| 24°F | Apr 5 | Apr 1 | Mar 29 | Mar 25 | Mar 20 | Mar 18 | Mar 14 | Mar 10 | Mar 5 |
| 20°F | Mar 29 | Mar 24 | Mar 19 | Mar 15 | Mar 12 | Mar 9 | Mar 6 | Mar 3 | Feb 27 |
| 16°F | Mar 20 | Mar 15 | Mar 11 | Mar 8 | Mar 5 | Mar 3 | Feb 28 | Feb 25 | Feb 18 |
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) | Oct 4 | Oct 19 | Oct 31 |
| Freeze (32°F) | Oct 17 | Oct 29 | Nov 10 |
| Hard (28°F) | Oct 27 | Nov 7 | Nov 21 |
| Severe (24°F) | Nov 4 | Nov 17 | Dec 2 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 4 | Oct 10 | Oct 14 | Oct 17 | Oct 19 | Oct 22 | Oct 24 | Oct 27 | Oct 31 |
| 32°F | Oct 17 | Oct 21 | Oct 25 | Oct 27 | Oct 29 | Oct 31 | Nov 2 | Nov 5 | Nov 10 |
| 28°F | Oct 27 | Oct 31 | Nov 2 | Nov 4 | Nov 7 | Nov 9 | Nov 12 | Nov 16 | Nov 21 |
| 24°F | Nov 4 | Nov 8 | Nov 11 | Nov 14 | Nov 17 | Nov 20 | Nov 23 | Nov 27 | Dec 2 |
| 20°F | Nov 9 | Nov 15 | Nov 19 | Nov 22 | Nov 26 | Nov 29 | Dec 2 | Dec 7 | Dec 13 |
| 16°F | Nov 18 | Nov 23 | Nov 27 | Dec 1 | Dec 3 | Dec 7 | Dec 11 | Dec 16 | Dec 21 |
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: Gladstone Dam 18, Il, about 11.3 miles away@if(!empty($station['elevation_ft'])), at 538 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 Mediapolis, IA?
On average, the last spring frost (32°F) around Mediapolis, IA is about Apr 8. In cooler years it can run later, so for a safer bet many gardeners wait until Mar 26.
When is the first frost in the fall?
The first fall frost around Mediapolis, IA typically arrives about Oct 29. 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 8 on average, or Mar 26 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 202 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 52637 Planting calendar → Iowa frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026