Index, WA frost dates
Last spring frostApr 14median date
First fall frostOct 29median date
Growing season198 daysfrost-free
Hardiness zone8aZone 8a
How Index compares
- In 8 years out of 10, the last spring frost in Index falls between March 26 and May 4, a 39-day window. The first fall frost falls between October 12 and November 16.
- The median last frost is 7 days earlier than the Washington median of Apr 21.
- Its 198-day growing season is longer than 58% of the 491 Washington places with a regular frost season (state median 182 days).
- The last frost is 16 days later than the zone 8a median of Mar 29. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 8a chart.
- The weather station records an average of 69 nights a year at or below 32°F.
- Compared with Sammamish, WA, 43 km away, the last frost here is 15 days later than there and the growing season is 24 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | March 26 |
| 50% (median) | April 14 |
| 10% (safe for tender plants) | May 4 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 12 |
| 50% (median) | October 29 |
| 90% (late) | November 16 |
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 Index, WA
Index, WA frost dates — last frost Apr 14, first frost Oct 29, zone 8a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Jan 20 to Feb 3Transplant outside: Mar 17 to Mar 31
Start indoors: Feb 3 to Feb 17Transplant outside: Apr 28 to May 12
Start indoors: Feb 3 to Feb 17Transplant outside: Apr 28 to May 12
Start indoors: Feb 17 to Mar 3Transplant outside: Apr 21 to May 5
Start indoors: Feb 17 to Mar 3Transplant outside: Mar 24 to Apr 7Sow outdoors: Mar 17 to Apr 21Plant for fall: Sep 3 to Oct 1
Start indoors: Feb 17 to Mar 3Transplant outside: Mar 17 to Mar 31Sow outdoors: Mar 17 to Mar 31Plant for fall: Aug 20 to Sep 10
Start indoors: Feb 17 to Mar 3Transplant outside: Mar 31 to Apr 14Plant for fall: Jul 23 to Aug 13
Start indoors: Feb 17 to Mar 3Transplant outside: Mar 24 to Apr 7Plant for fall: Jul 23 to Aug 13
Start indoors: Feb 17 to Mar 3Transplant outside: Mar 31 to Apr 14Plant for fall: Jul 23 to Aug 13
Start indoors: Mar 3 to Mar 17Transplant outside: May 5 to May 19Sow outdoors: May 5 to May 19
Start indoors: Mar 3 to Mar 17Transplant outside: Apr 21 to May 5
Sow outdoors: Mar 3 to Mar 24Plant for fall: Aug 6 to Aug 27
Sow outdoors: Mar 3 to Mar 24Plant for fall: Sep 3 to Sep 24
Sow outdoors: Mar 10 to Apr 21Plant for fall: Sep 17 to Oct 8
Start indoors: Mar 17 to Mar 24Transplant outside: Apr 28 to May 5Sow outdoors: Apr 21 to May 5Plant for fall: Aug 13 to Aug 27
Start indoors: Mar 17 to Mar 24Sow outdoors: Apr 21 to May 5Plant for fall: Aug 20 to Sep 3
Start indoors: Mar 17 to Mar 24Sow outdoors: Apr 21 to May 5
Start indoors: Mar 17 to Mar 24Transplant outside: Apr 28 to May 12
Sow outdoors: Mar 24 to Apr 21Plant for fall: Aug 6 to Aug 20
Sow outdoors: Mar 24 to Apr 21Plant for fall: Aug 20 to Sep 3
Sow outdoors: Mar 24 to Apr 14
Sow outdoors: Mar 31 to Apr 28Plant for fall: Aug 20 to Sep 3
Sow outdoors: Mar 31 to Apr 21Plant for fall: Sep 3 to Sep 24
Sow outdoors: Apr 21 to May 12Plant for fall: Aug 13 to Aug 27
Sow outdoors: Apr 21 to May 5
Transplant outside: Apr 28 to May 19
Plant for fall: Oct 15 to Nov 19
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Index, WA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 20 – Feb 3 | Mar 17 – Mar 31 | — | — |
| Peppers | Feb 3 – Feb 17 | Apr 28 – May 12 | — | — |
| Eggplant | Feb 3 – Feb 17 | Apr 28 – May 12 | — | — |
| Tomatoes | Feb 17 – Mar 3 | Apr 21 – May 5 | — | — |
| Lettuce | Feb 17 – Mar 3 | Mar 24 – Apr 7 | Mar 17 – Apr 21 | Sep 3 – Oct 1 |
| Kale | Feb 17 – Mar 3 | Mar 17 – Mar 31 | Mar 17 – Mar 31 | Aug 20 – Sep 10 |
| Broccoli | Feb 17 – Mar 3 | Mar 31 – Apr 14 | — | Jul 23 – Aug 13 |
| Cabbage | Feb 17 – Mar 3 | Mar 24 – Apr 7 | — | Jul 23 – Aug 13 |
| Cauliflower | Feb 17 – Mar 3 | Mar 31 – Apr 14 | — | Jul 23 – Aug 13 |
| Okra | Mar 3 – Mar 17 | May 5 – May 19 | May 5 – May 19 | — |
| Basil | Mar 3 – Mar 17 | Apr 21 – May 5 | — | — |
| Peas | — | — | Mar 3 – Mar 24 | Aug 6 – Aug 27 |
| Spinach | — | — | Mar 3 – Mar 24 | Sep 3 – Sep 24 |
| Radishes | — | — | Mar 10 – Apr 21 | Sep 17 – Oct 8 |
| Cucumbers | Mar 17 – Mar 24 | Apr 28 – May 5 | Apr 21 – May 5 | Aug 13 – Aug 27 |
| Zucchini & Summer Squash | Mar 17 – Mar 24 | — | Apr 21 – May 5 | Aug 20 – Sep 3 |
| Winter Squash & Pumpkins | Mar 17 – Mar 24 | — | Apr 21 – May 5 | — |
| Melons & Watermelon | Mar 17 – Mar 24 | Apr 28 – May 12 | — | — |
| Carrots | — | — | Mar 24 – Apr 21 | Aug 6 – Aug 20 |
| Beets | — | — | Mar 24 – Apr 21 | Aug 20 – Sep 3 |
| Potatoes | — | — | Mar 24 – Apr 14 | — |
| Swiss Chard | — | — | Mar 31 – Apr 28 | Aug 20 – Sep 3 |
| Cilantro | — | — | Mar 31 – Apr 21 | Sep 3 – Sep 24 |
| Green Beans | — | — | Apr 21 – May 12 | Aug 13 – Aug 27 |
| Sweet Corn | — | — | Apr 21 – May 5 | — |
| Sweet Potatoes | — | Apr 28 – May 19 | — | — |
| Garlic | — | — | — | Oct 15 – Nov 19 |
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 Baring, WA weather station, 7 km away (elevation 771 ft (235 m)).
Frost dates near Index
- Gold Bar Apr 15 · Oct 25
- Baring Apr 14 · Oct 29
- Sultan Apr 15 · Oct 25
- Startup Apr 15 · Oct 25
- Skykomish Apr 14 · Oct 29
- Monroe Apr 17 · Oct 23
- Duvall Apr 17 · Oct 23
- Carnation Mar 30 · Nov 7
- Fall City Mar 30 · Nov 7
- Snoqualmie Mar 30 · Nov 7
Frequently asked questions
When is the last frost in Index, WA?
The median last spring frost in Index, WA is April 14. There is still about a 10% chance of frost after May 4, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Index, WA?
The median first fall frost is October 29, with about a 10% chance of frost before October 12.
How long is the growing season in Index, WA?
About 198 days between the median last spring frost and first fall frost.
What planting zone is Index, WA?
Index, WA is in USDA hardiness zone 8a.