Alta, IA frost dates
Last spring frostApr 25median date
First fall frostOct 13median date
Growing season171 daysfrost-free
Hardiness zone5aZone 5a
How Alta compares
- In 8 years out of 10, the last spring frost in Alta falls between April 11 and May 7, a 26-day window. The first fall frost falls between October 1 and October 25.
- The median last frost is 3 days earlier than the Iowa median of Apr 28.
- Its 171-day growing season is longer than 72% of the 934 Iowa places with a regular frost season (state median 165 days).
- The last frost is 8 days earlier than the zone 5a median of May 3. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5a chart.
- The weather station records an average of 151 nights a year at or below 32°F.
- Compared with Sioux City, IA, 91 km away, the last frost here is 4 days earlier than there and the growing season is 10 days longer.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 11 |
| 50% (median) | April 25 |
| 10% (safe for tender plants) | May 7 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 1 |
| 50% (median) | October 13 |
| 90% (late) | October 25 |
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 Alta, IA
Alta, IA frost dates — last frost Apr 25, first frost Oct 13, zone 5a. whenisthelastfrost.com
Crop
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Start indoors: Jan 31 to Feb 14Transplant outside: Mar 28 to Apr 11
Start indoors: Feb 14 to Feb 28Transplant outside: May 9 to May 23
Start indoors: Feb 14 to Feb 28Transplant outside: May 9 to May 23
Start indoors: Feb 28 to Mar 14Transplant outside: May 2 to May 16
Start indoors: Feb 28 to Mar 14Transplant outside: Apr 4 to Apr 18Sow outdoors: Mar 28 to May 2Plant for fall: Aug 18 to Sep 15
Start indoors: Feb 28 to Mar 14Transplant outside: Mar 28 to Apr 11Sow outdoors: Mar 28 to Apr 11Plant for fall: Aug 4 to Aug 25
Start indoors: Feb 28 to Mar 14Transplant outside: Apr 11 to Apr 25Plant for fall: Jul 7 to Jul 28
Start indoors: Feb 28 to Mar 14Transplant outside: Apr 4 to Apr 18Plant for fall: Jul 7 to Jul 28
Start indoors: Feb 28 to Mar 14Transplant outside: Apr 11 to Apr 25Plant for fall: Jul 7 to Jul 28
Start indoors: Mar 14 to Mar 28Transplant outside: May 16 to May 30Sow outdoors: May 16 to May 30
Start indoors: Mar 14 to Mar 28Transplant outside: May 2 to May 16
Sow outdoors: Mar 14 to Apr 4Plant for fall: Jul 21 to Aug 11
Sow outdoors: Mar 14 to Apr 4Plant for fall: Aug 18 to Sep 8
Sow outdoors: Mar 21 to May 2Plant for fall: Sep 1 to Sep 22
Start indoors: Mar 28 to Apr 4Transplant outside: May 9 to May 16Sow outdoors: May 2 to May 16Plant for fall: Jul 28 to Aug 11
Start indoors: Mar 28 to Apr 4Sow outdoors: May 2 to May 16Plant for fall: Aug 4 to Aug 18
Start indoors: Mar 28 to Apr 4Sow outdoors: May 2 to May 16
Start indoors: Mar 28 to Apr 4Transplant outside: May 9 to May 23
Sow outdoors: Apr 4 to May 2Plant for fall: Jul 21 to Aug 4
Sow outdoors: Apr 4 to May 2Plant for fall: Aug 4 to Aug 18
Sow outdoors: Apr 4 to Apr 25
Sow outdoors: Apr 11 to May 9Plant for fall: Aug 4 to Aug 18
Sow outdoors: Apr 11 to May 2Plant for fall: Aug 18 to Sep 8
Sow outdoors: May 2 to May 23Plant for fall: Jul 28 to Aug 11
Sow outdoors: May 2 to May 16
Transplant outside: May 9 to May 30
Plant for fall: Sep 29 to Nov 3
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Alta, IA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 31 – Feb 14 | Mar 28 – Apr 11 | — | — |
| Peppers | Feb 14 – Feb 28 | May 9 – May 23 | — | — |
| Eggplant | Feb 14 – Feb 28 | May 9 – May 23 | — | — |
| Tomatoes | Feb 28 – Mar 14 | May 2 – May 16 | — | — |
| Lettuce | Feb 28 – Mar 14 | Apr 4 – Apr 18 | Mar 28 – May 2 | Aug 18 – Sep 15 |
| Kale | Feb 28 – Mar 14 | Mar 28 – Apr 11 | Mar 28 – Apr 11 | Aug 4 – Aug 25 |
| Broccoli | Feb 28 – Mar 14 | Apr 11 – Apr 25 | — | Jul 7 – Jul 28 |
| Cabbage | Feb 28 – Mar 14 | Apr 4 – Apr 18 | — | Jul 7 – Jul 28 |
| Cauliflower | Feb 28 – Mar 14 | Apr 11 – Apr 25 | — | Jul 7 – Jul 28 |
| Okra | Mar 14 – Mar 28 | May 16 – May 30 | May 16 – May 30 | — |
| Basil | Mar 14 – Mar 28 | May 2 – May 16 | — | — |
| Peas | — | — | Mar 14 – Apr 4 | Jul 21 – Aug 11 |
| Spinach | — | — | Mar 14 – Apr 4 | Aug 18 – Sep 8 |
| Radishes | — | — | Mar 21 – May 2 | Sep 1 – Sep 22 |
| Cucumbers | Mar 28 – Apr 4 | May 9 – May 16 | May 2 – May 16 | Jul 28 – Aug 11 |
| Zucchini & Summer Squash | Mar 28 – Apr 4 | — | May 2 – May 16 | Aug 4 – Aug 18 |
| Winter Squash & Pumpkins | Mar 28 – Apr 4 | — | May 2 – May 16 | — |
| Melons & Watermelon | Mar 28 – Apr 4 | May 9 – May 23 | — | — |
| Carrots | — | — | Apr 4 – May 2 | Jul 21 – Aug 4 |
| Beets | — | — | Apr 4 – May 2 | Aug 4 – Aug 18 |
| Potatoes | — | — | Apr 4 – Apr 25 | — |
| Swiss Chard | — | — | Apr 11 – May 9 | Aug 4 – Aug 18 |
| Cilantro | — | — | Apr 11 – May 2 | Aug 18 – Sep 8 |
| Green Beans | — | — | May 2 – May 23 | Jul 28 – Aug 11 |
| Sweet Corn | — | — | May 2 – May 16 | — |
| Sweet Potatoes | — | May 9 – May 30 | — | — |
| Garlic | — | — | — | Sep 29 – Nov 3 |
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 Storm Lake, IA weather station, 10 km away (elevation 1,444 ft (440 m)).
Frost dates near Alta
- Storm Lake Apr 25 · Oct 13
- Aurelia May 4 · Oct 4
- Truesdale Apr 25 · Oct 13
- Schaller Apr 25 · Oct 13
- Rembrandt Apr 30 · Oct 5
- Galva Apr 30 · Oct 9
- Cherokee May 4 · Oct 4
- Linn Grove Apr 30 · Oct 5
- Nemaha Apr 30 · Oct 6
- Newell Apr 25 · Oct 13
Frequently asked questions
When is the last frost in Alta, IA?
The median last spring frost in Alta, IA is April 25. There is still about a 10% chance of frost after May 7, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Alta, IA?
The median first fall frost is October 13, with about a 10% chance of frost before October 1.
How long is the growing season in Alta, IA?
About 171 days between the median last spring frost and first fall frost.
What planting zone is Alta, IA?
Alta, IA is in USDA hardiness zone 5a.