Charles City, IA frost dates
Last spring frostApr 30median date
First fall frostOct 6median date
Growing season159 daysfrost-free
Hardiness zone5aZone 5a
How Charles City compares
- In 8 years out of 10, the last spring frost in Charles City falls between April 15 and May 14, a 29-day window. The first fall frost falls between September 21 and October 19.
- The median last frost is 2 days later than the Iowa median of Apr 28.
- Its 159-day growing season is longer than 24% 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 154 nights a year at or below 32°F.
- Compared with Waterloo, IA, 71 km away, the last frost here is 3 days later than there and the growing season is 7 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 15 |
| 50% (median) | April 30 |
| 10% (safe for tender plants) | May 14 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 21 |
| 50% (median) | October 6 |
| 90% (late) | October 19 |
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 Charles City, IA
Charles City, IA frost dates — last frost Apr 30, first frost Oct 6, zone 5a. whenisthelastfrost.com
Crop
JFMAMJJASOND
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 11 to Sep 8
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 2 to Apr 16Sow outdoors: Apr 2 to Apr 16Plant for fall: Jul 28 to Aug 18
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 16 to Apr 30Plant for fall: Jun 30 to Jul 21
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 9 to Apr 23Plant for fall: Jun 30 to Jul 21
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 16 to Apr 30Plant for fall: Jun 30 to Jul 21
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 14 to Aug 4
Sow outdoors: Mar 19 to Apr 9Plant for fall: Aug 11 to Sep 1
Sow outdoors: Mar 26 to May 7Plant for fall: Aug 25 to Sep 15
Start indoors: Apr 2 to Apr 9Transplant outside: May 14 to May 21Sow outdoors: May 7 to May 21Plant for fall: Jul 21 to Aug 4
Start indoors: Apr 2 to Apr 9Sow outdoors: May 7 to May 21Plant for fall: Jul 28 to Aug 11
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 14 to Jul 28
Sow outdoors: Apr 9 to May 7Plant for fall: Jul 28 to Aug 11
Sow outdoors: Apr 9 to Apr 30
Sow outdoors: Apr 16 to May 14Plant for fall: Jul 28 to Aug 11
Sow outdoors: Apr 16 to May 7Plant for fall: Aug 11 to Sep 1
Sow outdoors: May 7 to May 28Plant for fall: Jul 21 to Aug 4
Sow outdoors: May 7 to May 21
Transplant outside: May 14 to Jun 4
Plant for fall: Sep 22 to Oct 27
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Charles City, 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 11 – Sep 8 |
| Kale | Mar 5 – Mar 19 | Apr 2 – Apr 16 | Apr 2 – Apr 16 | Jul 28 – Aug 18 |
| Broccoli | Mar 5 – Mar 19 | Apr 16 – Apr 30 | — | Jun 30 – Jul 21 |
| Cabbage | Mar 5 – Mar 19 | Apr 9 – Apr 23 | — | Jun 30 – Jul 21 |
| Cauliflower | Mar 5 – Mar 19 | Apr 16 – Apr 30 | — | Jun 30 – Jul 21 |
| 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 14 – Aug 4 |
| Spinach | — | — | Mar 19 – Apr 9 | Aug 11 – Sep 1 |
| Radishes | — | — | Mar 26 – May 7 | Aug 25 – Sep 15 |
| Cucumbers | Apr 2 – Apr 9 | May 14 – May 21 | May 7 – May 21 | Jul 21 – Aug 4 |
| Zucchini & Summer Squash | Apr 2 – Apr 9 | — | May 7 – May 21 | Jul 28 – Aug 11 |
| 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 14 – Jul 28 |
| Beets | — | — | Apr 9 – May 7 | Jul 28 – Aug 11 |
| Potatoes | — | — | Apr 9 – Apr 30 | — |
| Swiss Chard | — | — | Apr 16 – May 14 | Jul 28 – Aug 11 |
| Cilantro | — | — | Apr 16 – May 7 | Aug 11 – Sep 1 |
| Green Beans | — | — | May 7 – May 28 | Jul 21 – Aug 4 |
| Sweet Corn | — | — | May 7 – May 21 | — |
| Sweet Potatoes | — | May 14 – Jun 4 | — | — |
| Garlic | — | — | — | Sep 22 – Oct 27 |
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 Charles City, IA weather station, about 1 km away (elevation 994 ft (303 m)).
Frost dates near Charles City
- Floyd Apr 30 · Oct 6
- Colwell Apr 30 · Oct 6
- Ionia May 2 · Oct 5
- Nashua Apr 30 · Oct 6
- Orchard Apr 30 · Oct 9
- Rudd Apr 30 · Oct 9
- Marble Rock Apr 30 · Oct 6
- Greene Apr 27 · Oct 8
- North Washington May 2 · Oct 5
- Alta Vista May 2 · Oct 5
Frequently asked questions
When is the last frost in Charles City, IA?
The median last spring frost in Charles City, IA is April 30. There is still about a 10% chance of frost after May 14, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Charles City, IA?
The median first fall frost is October 6, with about a 10% chance of frost before September 21.
How long is the growing season in Charles City, IA?
About 159 days between the median last spring frost and first fall frost.
What planting zone is Charles City, IA?
Charles City, IA is in USDA hardiness zone 5a.