USDA Hardiness Zone 4b
Frost Dates for 83001 — Jackson, Wyoming
Averages from Moose, Wy US, the nearest reporting station, 13 miles away.
Plant tender crops after June 20, and expect the first autumn freeze around August 31. That leaves about 70 frost-free days.
- Last spring frost
- June 20
- First fall frost
- August 31
- Growing season
- 70 days
- Hardiness zone
- 4b
50% probability
50% probability
frost-free
-25 to -20°F annual low
Planting calendar for 83001
| When | What to do |
|---|---|
| April 11 – April 25 | Start peppers and aubergines indoors They need eight to ten weeks under lights before they can go out. |
| April 25 – May 9 | Start tomatoes indoors Six to eight weeks gives a transplant big enough to set fruit early. |
| May 23 – June 6 | Sow peas, spinach, lettuce, radish outdoors These tolerate light frost and prefer to germinate in cool soil. |
| June 20 onward | Transplant tomatoes, peppers, basil, squash, cucumbers The average last freeze has passed — still watch the actual forecast. |
| by June 8 | Sow the autumn crop of carrots, beets and brassicas They need about twelve weeks to size up before growth stops. |
| by August 17 | Harvest tender crops, or be ready to cover them A first freeze two weeks early is well within normal variation. |
| August 31 onward | Plant garlic, mulch beds, lift tender bulbs Garlic wants a cold spell; bare soil loses structure over winter. |
What these dates mean
Wait until after June 20 to put tender plants — tomatoes, peppers, basil, squash — in the ground. That is the date by which half of years in Jackson, Wyoming are past their last freeze. Harvest before August 31, which leaves roughly 70 frost-free days.
ZIP 83001 sits in USDA hardiness zone 4b, meaning the average coldest night of the year falls between -25 to -20°F. Zone decides what survives the winter; frost dates decide when to plant each spring. They are different questions, and a plant can pass one and fail the other.
These are thirty-year NOAA averages for 1991–2020, not a forecast. Any individual year can frost two to three weeks either side of these dates, so check the actual forecast before planting out.