Frost dates for Onawa, IA
When the last spring frost and first fall frost usually come, and when to plant, from 30 years of NOAA weather records.
Last spring frost
May 1
typical year
Safe to plant
May 13
frost is over in 9 of 10 years
First fall frost
October 3
typical year
Growing season
154 days
frost-free, typical year
Frost watch this week
Tonight's and the next six nights' lows from the National Weather Service forecast for the station's location. Frost: 32°F or colder. Possible frost: 33–36°F, mostly in low spots on clear, still nights.
When to plant
Counted from this page's frost dates. Warm-season crops wait for the safe-to-plant date.
| Crop | Start indoors | Plant outside | Fall planting |
|---|---|---|---|
| Cool-season crops | |||
| Peas | – | Apr 3 – 17 | – |
| Spinach | – | Mar 20 – Apr 10 | Aug 8 – 22 |
| Lettuce | – | Apr 3 – 24 | Aug 8 – 22 |
| Radishes | – | Apr 3 – May 15 | Aug 22 – Sep 5 |
| Onions | – | Apr 3 – 17 | – |
| Potatoes | – | Apr 10 – 24 | – |
| Carrots | – | Apr 10 – May 1 | Jul 11 – 25 |
| Beets | – | Apr 3 – 17 | Jul 25 – Aug 8 |
| Kale | Feb 20 – Mar 6 | Apr 3 – 17 | Jul 25 – Aug 8 |
| Broccoli | Feb 20 – Mar 6 | Apr 17 – May 1 | Jul 25 – Aug 8 |
| Cabbage | Feb 6 – 20 | Apr 3 – 17 | Jul 25 – Aug 8 |
| Garlic | – | – | Aug 22 – Sep 12 |
| Warm-season crops | |||
| Tomatoes | Mar 18 – Apr 1 | May 13 – 27 | – |
| Peppers | Mar 11 – 25 | May 20 – Jun 3 | – |
| Cucumbers | – | May 13 – Jun 3 | – |
| Zucchini | – | May 13 – Jun 10 | – |
| Pumpkins | – | May 13 – Jun 3 | – |
| Green beans | – | May 13 – Jul 25 | – |
| Sweet corn | – | May 13 – Jun 10 | – |
| Basil | Apr 8 – 22 | May 20 – 27 | – |
Onions: from sets. Green beans: until 10 weeks before the first fall frost. Garlic: harvest next summer.
The year at a glance
Start indoors Plant outside Fall planting
The chance of frost, by date
| 1 year in 10 | Half of years | 9 years in 10 | |
|---|---|---|---|
| Spring frost after | May 13 | May 1 | April 19 |
| Fall frost before | September 21 | October 3 | October 18 |
Frost here means 32°F or colder. Read across: in 1 year in 10, spring frost carries on past the first date, which is why that date is the safe-to-plant date.
Hard freeze (28°F)
A hard freeze kills most garden plants, even hardy ones. The last one in spring usually comes around April 22 (May 6 in a late year), and the first one in fall around October 13.
Towns that use these dates
This is the nearest NOAA station with frost records for 5 towns.
Onawa, Sloan, Whiting, Decatur, NE, Hornick
Where these dates come from
NOAA weather station ONAWA 3NW, IA US (USC00136243), 1991–2020 climate normals. It's the nearest station for 4 zip codes, all within 13 miles:
51026, 51040, 51063, 68020
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.