Opheim, MT frost dates
Last spring frostJun 1median date
First fall frostSep 7median date
Growing season98 daysfrost-free
Hardiness zone3bZone 3b
How Opheim compares
- In 8 years out of 10, the last spring frost in Opheim falls between May 20 and June 18, a 29-day window. The first fall frost falls between August 24 and September 21.
- The median last frost is 13 days later than the Montana median of May 19.
- Its 98-day growing season is longer than 10% of the 325 Montana places with a regular frost season (state median 125 days).
- The last frost is 15 days later than the zone 3b median of May 17. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 3b chart.
- The weather station records an average of 210 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 20 |
| 50% (median) | June 1 |
| 10% (safe for tender plants) | June 18 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | August 24 |
| 50% (median) | September 7 |
| 90% (late) | September 21 |
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 Opheim, MT
Opheim, MT frost dates — last frost Jun 1, first frost Sep 7, zone 3b. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Mar 9 to Mar 23Transplant outside: May 4 to May 18
Start indoors: Mar 23 to Apr 6Transplant outside: Jun 15 to Jun 29
Start indoors: Mar 23 to Apr 6Transplant outside: Jun 15 to Jun 29
Start indoors: Apr 6 to Apr 20Transplant outside: Jun 8 to Jun 22
Start indoors: Apr 6 to Apr 20Transplant outside: May 11 to May 25Sow outdoors: May 4 to Jun 8Plant for fall: Jul 13 to Aug 10
Start indoors: Apr 6 to Apr 20Transplant outside: May 4 to May 18Sow outdoors: May 4 to May 18Plant for fall: Jun 29 to Jul 20
Start indoors: Apr 6 to Apr 20Transplant outside: May 18 to Jun 1
Start indoors: Apr 6 to Apr 20Transplant outside: May 11 to May 25
Start indoors: Apr 6 to Apr 20Transplant outside: May 18 to Jun 1
Start indoors: Apr 20 to May 4Transplant outside: Jun 22 to Jul 6Sow outdoors: Jun 22 to Jul 6
Start indoors: Apr 20 to May 4Transplant outside: Jun 8 to Jun 22
Sow outdoors: Apr 20 to May 11
Sow outdoors: Apr 20 to May 11Plant for fall: Jul 13 to Aug 3
Sow outdoors: Apr 27 to Jun 8Plant for fall: Jul 27 to Aug 17
Start indoors: May 4 to May 11Transplant outside: Jun 15 to Jun 22Sow outdoors: Jun 8 to Jun 22
Start indoors: May 4 to May 11Sow outdoors: Jun 8 to Jun 22
Start indoors: May 4 to May 11Sow outdoors: Jun 8 to Jun 22
Start indoors: May 4 to May 11Transplant outside: Jun 15 to Jun 29
Sow outdoors: May 11 to Jun 8
Sow outdoors: May 11 to Jun 8Plant for fall: Jun 29 to Jul 13
Sow outdoors: May 11 to Jun 1
Sow outdoors: May 18 to Jun 15
Sow outdoors: May 18 to Jun 8Plant for fall: Jul 13 to Aug 3
Sow outdoors: Jun 8 to Jun 29
Sow outdoors: Jun 8 to Jun 22
Transplant outside: Jun 15 to Jul 6
Plant for fall: Aug 24 to Sep 28
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Opheim, MT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 9 – Mar 23 | May 4 – May 18 | — | — |
| Peppers | Mar 23 – Apr 6 | Jun 15 – Jun 29 | — | — |
| Eggplant | Mar 23 – Apr 6 | Jun 15 – Jun 29 | — | — |
| Tomatoes | Apr 6 – Apr 20 | Jun 8 – Jun 22 | — | — |
| Lettuce | Apr 6 – Apr 20 | May 11 – May 25 | May 4 – Jun 8 | Jul 13 – Aug 10 |
| Kale | Apr 6 – Apr 20 | May 4 – May 18 | May 4 – May 18 | Jun 29 – Jul 20 |
| Broccoli | Apr 6 – Apr 20 | May 18 – Jun 1 | — | — |
| Cabbage | Apr 6 – Apr 20 | May 11 – May 25 | — | — |
| Cauliflower | Apr 6 – Apr 20 | May 18 – Jun 1 | — | — |
| Okra | Apr 20 – May 4 | Jun 22 – Jul 6 | Jun 22 – Jul 6 | — |
| Basil | Apr 20 – May 4 | Jun 8 – Jun 22 | — | — |
| Peas | — | — | Apr 20 – May 11 | — |
| Spinach | — | — | Apr 20 – May 11 | Jul 13 – Aug 3 |
| Radishes | — | — | Apr 27 – Jun 8 | Jul 27 – Aug 17 |
| Cucumbers | May 4 – May 11 | Jun 15 – Jun 22 | Jun 8 – Jun 22 | — |
| Zucchini & Summer Squash | May 4 – May 11 | — | Jun 8 – Jun 22 | — |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 98 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | May 4 – May 11 | — | Jun 8 – Jun 22 | — |
| Melons & Watermelon Warning: Your frost-free season is about 98 days, which is tight for melons & watermelon (85+ days). Choose early varieties and use transplants or row covers. | May 4 – May 11 | Jun 15 – Jun 29 | — | — |
| Carrots | — | — | May 11 – Jun 8 | — |
| Beets | — | — | May 11 – Jun 8 | Jun 29 – Jul 13 |
| Potatoes | — | — | May 11 – Jun 1 | — |
| Swiss Chard | — | — | May 18 – Jun 15 | — |
| Cilantro | — | — | May 18 – Jun 8 | Jul 13 – Aug 3 |
| Green Beans | — | — | Jun 8 – Jun 29 | — |
| Sweet Corn | — | — | Jun 8 – Jun 22 | — |
| Sweet Potatoes Warning: Your frost-free season is about 98 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 15 – Jul 6 | — | — |
| Garlic | — | — | — | Aug 24 – Sep 28 |
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 Opheim 10 N, MT weather station, 14 km away (elevation 2,877 ft (877 m)).
Frost dates near Opheim
- Glentana Jun 5 · Sep 2
- Richland Jun 5 · Sep 2
- Larslan Jun 5 · Sep 2
- Peerless May 28 · Sep 6
- Saint Marie May 13 · Sep 27
- Frazer May 12 · Sep 24
- Vandalia May 15 · Sep 26
- Scobey May 28 · Sep 6
- Hinsdale May 15 · Sep 26
- Glasgow May 6 · Sep 30
Frequently asked questions
When is the last frost in Opheim, MT?
The median last spring frost in Opheim, MT is June 1. There is still about a 10% chance of frost after June 18, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Opheim, MT?
The median first fall frost is September 7, with about a 10% chance of frost before August 24.
How long is the growing season in Opheim, MT?
About 98 days between the median last spring frost and first fall frost.
What planting zone is Opheim, MT?
Opheim, MT is in USDA hardiness zone 3b.