Alta, WY frost dates
Last spring frostJun 14median date
First fall frostSep 11median date
Growing season89 daysfrost-free
Hardiness zone5aZone 5a
How Alta compares
- In 8 years out of 10, the last spring frost in Alta falls between May 23 and July 4, a 42-day window. The first fall frost falls between August 28 and September 26.
- The median last frost is 24 days later than the Wyoming median of May 21.
- Its 89-day growing season is longer than 10% of the 153 Wyoming places with a regular frost season (state median 125 days).
- The last frost is 42 days later 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 204 nights a year at or below 32°F.
- Compared with Idaho Falls, ID, 96 km away, the last frost here is 36 days later than there and the growing season is 56 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 23 |
| 50% (median) | June 14 |
| 10% (safe for tender plants) | July 4 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | August 28 |
| 50% (median) | September 11 |
| 90% (late) | September 26 |
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, WY
Alta, WY frost dates — last frost Jun 14, first frost Sep 11, zone 5a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Mar 22 to Apr 5Transplant outside: May 17 to May 31
Start indoors: Apr 5 to Apr 19Transplant outside: Jun 28 to Jul 12
Start indoors: Apr 5 to Apr 19Transplant outside: Jun 28 to Jul 12
Start indoors: Apr 19 to May 3Transplant outside: Jun 21 to Jul 5
Start indoors: Apr 19 to May 3Transplant outside: May 24 to Jun 7Sow outdoors: May 17 to Jun 21Plant for fall: Jul 17 to Aug 14
Start indoors: Apr 19 to May 3Transplant outside: May 17 to May 31Sow outdoors: May 17 to May 31Plant for fall: Jul 3 to Jul 24
Start indoors: Apr 19 to May 3Transplant outside: May 31 to Jun 14
Start indoors: Apr 19 to May 3Transplant outside: May 24 to Jun 7
Start indoors: Apr 19 to May 3Transplant outside: May 31 to Jun 14
Start indoors: May 3 to May 17Transplant outside: Jul 5 to Jul 19Sow outdoors: Jul 5 to Jul 19
Start indoors: May 3 to May 17Transplant outside: Jun 21 to Jul 5
Sow outdoors: May 3 to May 24
Sow outdoors: May 3 to May 24Plant for fall: Jul 17 to Aug 7
Sow outdoors: May 10 to Jun 21Plant for fall: Jul 31 to Aug 21
Start indoors: May 17 to May 24Transplant outside: Jun 28 to Jul 5Sow outdoors: Jun 21 to Jul 5
Start indoors: May 17 to May 24Sow outdoors: Jun 21 to Jul 5
Start indoors: May 17 to May 24Sow outdoors: Jun 21 to Jul 5
Start indoors: May 17 to May 24Transplant outside: Jun 28 to Jul 12
Sow outdoors: May 24 to Jun 21
Sow outdoors: May 24 to Jun 21
Sow outdoors: May 24 to Jun 14
Sow outdoors: May 31 to Jun 28
Sow outdoors: May 31 to Jun 21Plant for fall: Jul 17 to Aug 7
Sow outdoors: Jun 21 to Jul 12
Sow outdoors: Jun 21 to Jul 5
Transplant outside: Jun 28 to Jul 19
Plant for fall: Aug 28 to Oct 2
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Alta, WY
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 22 – Apr 5 | May 17 – May 31 | — | — |
| Peppers | Apr 5 – Apr 19 | Jun 28 – Jul 12 | — | — |
| Eggplant | Apr 5 – Apr 19 | Jun 28 – Jul 12 | — | — |
| Tomatoes | Apr 19 – May 3 | Jun 21 – Jul 5 | — | — |
| Lettuce | Apr 19 – May 3 | May 24 – Jun 7 | May 17 – Jun 21 | Jul 17 – Aug 14 |
| Kale | Apr 19 – May 3 | May 17 – May 31 | May 17 – May 31 | Jul 3 – Jul 24 |
| Broccoli | Apr 19 – May 3 | May 31 – Jun 14 | — | — |
| Cabbage | Apr 19 – May 3 | May 24 – Jun 7 | — | — |
| Cauliflower | Apr 19 – May 3 | May 31 – Jun 14 | — | — |
| Okra | May 3 – May 17 | Jul 5 – Jul 19 | Jul 5 – Jul 19 | — |
| Basil | May 3 – May 17 | Jun 21 – Jul 5 | — | — |
| Peas | — | — | May 3 – May 24 | — |
| Spinach | — | — | May 3 – May 24 | Jul 17 – Aug 7 |
| Radishes | — | — | May 10 – Jun 21 | Jul 31 – Aug 21 |
| Cucumbers | May 17 – May 24 | Jun 28 – Jul 5 | Jun 21 – Jul 5 | — |
| Zucchini & Summer Squash | May 17 – May 24 | — | Jun 21 – Jul 5 | — |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 89 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | May 17 – May 24 | — | Jun 21 – Jul 5 | — |
| Melons & Watermelon Warning: Your frost-free season is about 89 days, which is tight for melons & watermelon (85+ days). Choose early varieties and use transplants or row covers. | May 17 – May 24 | Jun 28 – Jul 12 | — | — |
| Carrots | — | — | May 24 – Jun 21 | — |
| Beets | — | — | May 24 – Jun 21 | — |
| Potatoes | — | — | May 24 – Jun 14 | — |
| Swiss Chard | — | — | May 31 – Jun 28 | — |
| Cilantro | — | — | May 31 – Jun 21 | Jul 17 – Aug 7 |
| Green Beans | — | — | Jun 21 – Jul 12 | — |
| Sweet Corn Warning: Your frost-free season is about 89 days, which is tight for sweet corn (80+ days). Choose early varieties and use transplants or row covers. | — | — | Jun 21 – Jul 5 | — |
| Sweet Potatoes Warning: Your frost-free season is about 89 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 28 – Jul 19 | — | — |
| Garlic | — | — | — | Aug 28 – Oct 2 |
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 Alta 1 Nnw, WY weather station, 15 km away (elevation 6,440 ft (1,963 m)).
Frost dates near Alta
- Moose Jun 24 · Aug 28
- Moran frost any month
- Teton Village Jun 20 · Aug 31
- Wilson frost any month
- Kelly Jun 24 · Aug 28
- Jackson frost any month
- Alpine frost any month
- Bondurant frost any month
- Etna frost any month
- Freedom frost any month
Frequently asked questions
When is the last frost in Alta, WY?
The median last spring frost in Alta, WY is June 14. There is still about a 10% chance of frost after July 4, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Alta, WY?
The median first fall frost is September 11, with about a 10% chance of frost before August 28.
How long is the growing season in Alta, WY?
About 89 days between the median last spring frost and first fall frost.
What planting zone is Alta, WY?
Alta, WY is in USDA hardiness zone 5a.