Frost dates for Ice Harbor Dam, WA
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
April 7
typical year
Safe to plant
April 30
frost is over in 9 of 10 years
First fall frost
October 22
typical year
Growing season
199 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 | – | Mar 10 – 24 | – |
| Spinach | – | Feb 24 – Mar 17 | Aug 27 – Sep 10 |
| Lettuce | – | Mar 10 – 31 | Aug 27 – Sep 10 |
| Radishes | – | Mar 10 – Apr 21 | Sep 10 – 24 |
| Onions | – | Mar 10 – 24 | – |
| Potatoes | – | Mar 17 – 31 | – |
| Carrots | – | Mar 17 – Apr 7 | Jul 30 – Aug 13 |
| Beets | – | Mar 10 – 24 | Aug 13 – 27 |
| Kale | Jan 27 – Feb 10 | Mar 10 – 24 | Aug 13 – 27 |
| Broccoli | Jan 27 – Feb 10 | Mar 24 – Apr 7 | Aug 13 – 27 |
| Cabbage | Jan 13 – 27 | Mar 10 – 24 | Aug 13 – 27 |
| Garlic | – | – | Sep 10 – Oct 1 |
| Warm-season crops | |||
| Tomatoes | Mar 5 – 19 | Apr 30 – May 14 | – |
| Peppers | Feb 26 – Mar 12 | May 7 – 21 | – |
| Cucumbers | – | Apr 30 – May 21 | – |
| Zucchini | – | Apr 30 – May 28 | – |
| Pumpkins | – | Apr 30 – May 21 | – |
| Green beans | – | Apr 30 – Aug 13 | – |
| Sweet corn | – | Apr 30 – May 28 | – |
| Basil | Mar 26 – Apr 9 | May 7 – 14 | – |
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 | April 30 | April 7 | March 20 |
| Fall frost before | October 6 | October 22 | November 9 |
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 March 18 (April 7 in a late year), and the first one in fall around November 4.
Where these dates come from
NOAA weather station ICE HARBOR DAM, WA US (USC00453883), 1991–2020 climate normals. It's the nearest station for 2 zip codes, all within 14 miles:
99323, 99363
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.