Hysham, MT frost dates
Last spring frostMay 10median date
First fall frostSep 29median date
Growing season142 daysfrost-free
Hardiness zone4bZone 4b
How Hysham compares
- In 8 years out of 10, the last spring frost in Hysham falls between April 28 and May 22, a 24-day window. The first fall frost falls between September 15 and October 11.
- The median last frost is 9 days earlier than the Montana median of May 19.
- Its 142-day growing season is longer than 83% of the 325 Montana places with a regular frost season (state median 125 days).
- The last frost is typical for zone 4b, where the median is May 8.
- The weather station records an average of 161 nights a year at or below 32°F.
- Compared with Billings, MT, 107 km away, the last frost here is 6 days later than there and the growing season is 14 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 28 |
| 50% (median) | May 10 |
| 10% (safe for tender plants) | May 22 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 15 |
| 50% (median) | September 29 |
| 90% (late) | October 11 |
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 Hysham, MT
Hysham, MT frost dates — last frost May 10, first frost Sep 29, zone 4b. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Feb 15 to Mar 1Transplant outside: Apr 12 to Apr 26
Start indoors: Mar 1 to Mar 15Transplant outside: May 24 to Jun 7
Start indoors: Mar 1 to Mar 15Transplant outside: May 24 to Jun 7
Start indoors: Mar 15 to Mar 29Transplant outside: May 17 to May 31
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 19 to May 3Sow outdoors: Apr 12 to May 17Plant for fall: Aug 4 to Sep 1
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 12 to Apr 26Sow outdoors: Apr 12 to Apr 26Plant for fall: Jul 21 to Aug 11
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 26 to May 10Plant for fall: Jun 23 to Jul 14
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 19 to May 3Plant for fall: Jun 23 to Jul 14
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 26 to May 10Plant for fall: Jun 23 to Jul 14
Start indoors: Mar 29 to Apr 12Transplant outside: May 31 to Jun 14Sow outdoors: May 31 to Jun 14
Start indoors: Mar 29 to Apr 12Transplant outside: May 17 to May 31
Sow outdoors: Mar 29 to Apr 19Plant for fall: Jul 7 to Jul 28
Sow outdoors: Mar 29 to Apr 19Plant for fall: Aug 4 to Aug 25
Sow outdoors: Apr 5 to May 17Plant for fall: Aug 18 to Sep 8
Start indoors: Apr 12 to Apr 19Transplant outside: May 24 to May 31Sow outdoors: May 17 to May 31Plant for fall: Jul 14 to Jul 28
Start indoors: Apr 12 to Apr 19Sow outdoors: May 17 to May 31Plant for fall: Jul 21 to Aug 4
Start indoors: Apr 12 to Apr 19Sow outdoors: May 17 to May 31
Start indoors: Apr 12 to Apr 19Transplant outside: May 24 to Jun 7
Sow outdoors: Apr 19 to May 17Plant for fall: Jul 7 to Jul 21
Sow outdoors: Apr 19 to May 17Plant for fall: Jul 21 to Aug 4
Sow outdoors: Apr 19 to May 10
Sow outdoors: Apr 26 to May 24Plant for fall: Jul 21 to Aug 4
Sow outdoors: Apr 26 to May 17Plant for fall: Aug 4 to Aug 25
Sow outdoors: May 17 to Jun 7Plant for fall: Jul 14 to Jul 28
Sow outdoors: May 17 to May 31
Transplant outside: May 24 to Jun 14
Plant for fall: Sep 15 to Oct 20
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Hysham, MT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 15 – Mar 1 | Apr 12 – Apr 26 | — | — |
| Peppers | Mar 1 – Mar 15 | May 24 – Jun 7 | — | — |
| Eggplant | Mar 1 – Mar 15 | May 24 – Jun 7 | — | — |
| Tomatoes | Mar 15 – Mar 29 | May 17 – May 31 | — | — |
| Lettuce | Mar 15 – Mar 29 | Apr 19 – May 3 | Apr 12 – May 17 | Aug 4 – Sep 1 |
| Kale | Mar 15 – Mar 29 | Apr 12 – Apr 26 | Apr 12 – Apr 26 | Jul 21 – Aug 11 |
| Broccoli | Mar 15 – Mar 29 | Apr 26 – May 10 | — | Jun 23 – Jul 14 |
| Cabbage | Mar 15 – Mar 29 | Apr 19 – May 3 | — | Jun 23 – Jul 14 |
| Cauliflower | Mar 15 – Mar 29 | Apr 26 – May 10 | — | Jun 23 – Jul 14 |
| Okra | Mar 29 – Apr 12 | May 31 – Jun 14 | May 31 – Jun 14 | — |
| Basil | Mar 29 – Apr 12 | May 17 – May 31 | — | — |
| Peas | — | — | Mar 29 – Apr 19 | Jul 7 – Jul 28 |
| Spinach | — | — | Mar 29 – Apr 19 | Aug 4 – Aug 25 |
| Radishes | — | — | Apr 5 – May 17 | Aug 18 – Sep 8 |
| Cucumbers | Apr 12 – Apr 19 | May 24 – May 31 | May 17 – May 31 | Jul 14 – Jul 28 |
| Zucchini & Summer Squash | Apr 12 – Apr 19 | — | May 17 – May 31 | Jul 21 – Aug 4 |
| Winter Squash & Pumpkins | Apr 12 – Apr 19 | — | May 17 – May 31 | — |
| Melons & Watermelon | Apr 12 – Apr 19 | May 24 – Jun 7 | — | — |
| Carrots | — | — | Apr 19 – May 17 | Jul 7 – Jul 21 |
| Beets | — | — | Apr 19 – May 17 | Jul 21 – Aug 4 |
| Potatoes | — | — | Apr 19 – May 10 | — |
| Swiss Chard | — | — | Apr 26 – May 24 | Jul 21 – Aug 4 |
| Cilantro | — | — | Apr 26 – May 17 | Aug 4 – Aug 25 |
| Green Beans | — | — | May 17 – Jun 7 | Jul 14 – Jul 28 |
| Sweet Corn | — | — | May 17 – May 31 | — |
| Sweet Potatoes | — | May 24 – Jun 14 | — | — |
| Garlic | — | — | — | Sep 15 – Oct 20 |
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 Hysham, MT weather station, 6 km away (elevation 2,671 ft (814 m)).
Frost dates near Hysham
- Sanders May 10 · Sep 29
- Custer May 22 · Sep 22
- Bighorn May 26 · Sep 16
- Ingomar May 21 · Sep 19
- Sumatra May 10 · Sep 29
- Forsyth May 9 · Sep 29
- Melstone May 10 · Sep 29
- Pompeys Pillar May 22 · Sep 22
- Hardin May 13 · Sep 29
- Colstrip May 15 · Sep 30
Frequently asked questions
When is the last frost in Hysham, MT?
The median last spring frost in Hysham, MT is May 10. There is still about a 10% chance of frost after May 22, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Hysham, MT?
The median first fall frost is September 29, with about a 10% chance of frost before September 15.
How long is the growing season in Hysham, MT?
About 142 days between the median last spring frost and first fall frost.
What planting zone is Hysham, MT?
Hysham, MT is in USDA hardiness zone 4b.