Thompson, IA frost dates
Last spring frostApr 30median date
First fall frostOct 7median date
Growing season160 daysfrost-free
Hardiness zone5aZone 5a
How Thompson compares
- In 8 years out of 10, the last spring frost in Thompson falls between April 14 and May 10, a 26-day window. The first fall frost falls between September 22 and October 20.
- The median last frost is 2 days later than the Iowa median of Apr 28.
- Its 160-day growing season is longer than 27% of the 934 Iowa places with a regular frost season (state median 165 days).
- The last frost is typical for zone 5a, where the median is May 3.
- The weather station records an average of 159 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 14 |
| 50% (median) | April 30 |
| 10% (safe for tender plants) | May 10 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 22 |
| 50% (median) | October 7 |
| 90% (late) | October 20 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Thompson, IA
Thompson, IA frost dates — last frost Apr 30, first frost Oct 7, zone 5a. whenisthelastfrost.com
Crop
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Start indoors: Feb 5 to Feb 19Transplant outside: Apr 2 to Apr 16
Start indoors: Feb 19 to Mar 5Transplant outside: May 14 to May 28
Start indoors: Feb 19 to Mar 5Transplant outside: May 14 to May 28
Start indoors: Mar 5 to Mar 19Transplant outside: May 7 to May 21
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 9 to Apr 23Sow outdoors: Apr 2 to May 7Plant for fall: Aug 12 to Sep 9
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 2 to Apr 16Sow outdoors: Apr 2 to Apr 16Plant for fall: Jul 29 to Aug 19
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 16 to Apr 30Plant for fall: Jul 1 to Jul 22
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 9 to Apr 23Plant for fall: Jul 1 to Jul 22
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 16 to Apr 30Plant for fall: Jul 1 to Jul 22
Start indoors: Mar 19 to Apr 2Transplant outside: May 21 to Jun 4Sow outdoors: May 21 to Jun 4
Start indoors: Mar 19 to Apr 2Transplant outside: May 7 to May 21
Sow outdoors: Mar 19 to Apr 9Plant for fall: Jul 15 to Aug 5
Sow outdoors: Mar 19 to Apr 9Plant for fall: Aug 12 to Sep 2
Sow outdoors: Mar 26 to May 7Plant for fall: Aug 26 to Sep 16
Start indoors: Apr 2 to Apr 9Transplant outside: May 14 to May 21Sow outdoors: May 7 to May 21Plant for fall: Jul 22 to Aug 5
Start indoors: Apr 2 to Apr 9Sow outdoors: May 7 to May 21Plant for fall: Jul 29 to Aug 12
Start indoors: Apr 2 to Apr 9Sow outdoors: May 7 to May 21
Start indoors: Apr 2 to Apr 9Transplant outside: May 14 to May 28
Sow outdoors: Apr 9 to May 7Plant for fall: Jul 15 to Jul 29
Sow outdoors: Apr 9 to May 7Plant for fall: Jul 29 to Aug 12
Sow outdoors: Apr 9 to Apr 30
Sow outdoors: Apr 16 to May 14Plant for fall: Jul 29 to Aug 12
Sow outdoors: Apr 16 to May 7Plant for fall: Aug 12 to Sep 2
Sow outdoors: May 7 to May 28Plant for fall: Jul 22 to Aug 5
Sow outdoors: May 7 to May 21
Transplant outside: May 14 to Jun 4
Plant for fall: Sep 23 to Oct 28
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Thompson, IA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 5 – Feb 19 | Apr 2 – Apr 16 | — | — |
| Peppers | Feb 19 – Mar 5 | May 14 – May 28 | — | — |
| Eggplant | Feb 19 – Mar 5 | May 14 – May 28 | — | — |
| Tomatoes | Mar 5 – Mar 19 | May 7 – May 21 | — | — |
| Lettuce | Mar 5 – Mar 19 | Apr 9 – Apr 23 | Apr 2 – May 7 | Aug 12 – Sep 9 |
| Kale | Mar 5 – Mar 19 | Apr 2 – Apr 16 | Apr 2 – Apr 16 | Jul 29 – Aug 19 |
| Broccoli | Mar 5 – Mar 19 | Apr 16 – Apr 30 | — | Jul 1 – Jul 22 |
| Cabbage | Mar 5 – Mar 19 | Apr 9 – Apr 23 | — | Jul 1 – Jul 22 |
| Cauliflower | Mar 5 – Mar 19 | Apr 16 – Apr 30 | — | Jul 1 – Jul 22 |
| Okra | Mar 19 – Apr 2 | May 21 – Jun 4 | May 21 – Jun 4 | — |
| Basil | Mar 19 – Apr 2 | May 7 – May 21 | — | — |
| Peas | — | — | Mar 19 – Apr 9 | Jul 15 – Aug 5 |
| Spinach | — | — | Mar 19 – Apr 9 | Aug 12 – Sep 2 |
| Radishes | — | — | Mar 26 – May 7 | Aug 26 – Sep 16 |
| Cucumbers | Apr 2 – Apr 9 | May 14 – May 21 | May 7 – May 21 | Jul 22 – Aug 5 |
| Zucchini & Summer Squash | Apr 2 – Apr 9 | — | May 7 – May 21 | Jul 29 – Aug 12 |
| Winter Squash & Pumpkins | Apr 2 – Apr 9 | — | May 7 – May 21 | — |
| Melons & Watermelon | Apr 2 – Apr 9 | May 14 – May 28 | — | — |
| Carrots | — | — | Apr 9 – May 7 | Jul 15 – Jul 29 |
| Beets | — | — | Apr 9 – May 7 | Jul 29 – Aug 12 |
| Potatoes | — | — | Apr 9 – Apr 30 | — |
| Swiss Chard | — | — | Apr 16 – May 14 | Jul 29 – Aug 12 |
| Cilantro | — | — | Apr 16 – May 7 | Aug 12 – Sep 2 |
| Green Beans | — | — | May 7 – May 28 | Jul 22 – Aug 5 |
| Sweet Corn | — | — | May 7 – May 21 | — |
| Sweet Potatoes | — | May 14 – Jun 4 | — | — |
| Garlic | — | — | — | Sep 23 – Oct 28 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Forest City 2 Nne, IA weather station, 15 km away (elevation 1,280 ft (390 m)).
Frost dates near Thompson
- Leland Apr 30 · Oct 7
- Scarville Apr 30 · Oct 7
- Buffalo Center Apr 30 · Oct 7
- Forest City Apr 30 · Oct 7
- Rake Apr 30 · Oct 7
- Lake Mills Apr 30 · Oct 7
- Crystal Lake Apr 29 · Oct 7
- Woden Apr 29 · Oct 7
- Joice Apr 30 · Oct 7
- Lakota May 4 · Oct 1
Frequently asked questions
When is the last frost in Thompson, IA?
The median last spring frost in Thompson, IA is April 30. There is still about a 10% chance of frost after May 10, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Thompson, IA?
The median first fall frost is October 7, with about a 10% chance of frost before September 22.
How long is the growing season in Thompson, IA?
About 160 days between the median last spring frost and first fall frost.
What planting zone is Thompson, IA?
Thompson, IA is in USDA hardiness zone 5a.