The last 36°F Spring frost date is 30% likely to be on Jun 8. (See detailed probabilities below.)
The last 32°F light freeze date is 30% likely to be on May 21. (See detailed probabilities below.)
(See also 🍂 First Fall Frost Dates.)
Last frost date probabilities for East Helena, MT are based on historical climate data.
Always check your local forecast for the most up-to-date frost warnings.
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📚 Growing Under Cover: Techniques for a More Productive, Weather-Resistant, Pest-Free Vegetable Garden
The last spring frost signals when your area is safe from freezing temperatures. Tender plants can now grow outdoors without cold damage! This marks the beginning of the growing season. Last spring frost serves as your essential starting point for planting warm-season crops. It's also time to remove winter protection from your perennials. Enjoy the longer days and warmer weather!
Start seeds indoors several weeks before your last frost date. This gives plants time to reach transplanting size when weather permits. Plan your outdoor planting schedule around your area's average last frost date. Plant some crops before and some after this date to protect against weather changes. Look for spots in your yard where frost stays longer or disappears earlier. Create your own frost map to use all available growing space and extend your season. Keep watching your local weather forecast to catch any surprise late frosts.
| Probability of frost (36°F) on or after… | |
|---|---|
| 10% chance | Jun 18 |
| 20% chance | Jun 13 |
| 30% chance | Jun 8 |
| 40% chance | Jun 5 |
| 50% chance | Jun 2 |
| 60% chance | May 30 |
| 70% chance | May 27 |
| 80% chance | May 22 |
| 90% chance | May 17 |
| Probability of light freeze (32°F) on or after… | |
|---|---|
| 10% chance | Jun 1 |
| 20% chance | May 25 |
| 30% chance | May 21 |
| 40% chance | May 17 |
| 50% chance | May 14 |
| 60% chance | May 11 |
| 70% chance | May 8 |
| 80% chance | May 5 |
| 90% chance | May 1 |
| Probability of moderate freeze (28°F) on or after… | |
|---|---|
| 10% chance | May 14 |
| 20% chance | May 9 |
| 30% chance | May 5 |
| 40% chance | May 2 |
| 50% chance | Apr 30 |
| 60% chance | Apr 27 |
| 70% chance | Apr 23 |
| 80% chance | Apr 19 |
| 90% chance | Apr 13 |
| Probability of moderate hard freeze (24°F) on or after… | |
|---|---|
| 10% chance | May 1 |
| 20% chance | Apr 27 |
| 30% chance | Apr 22 |
| 40% chance | Apr 18 |
| 50% chance | Apr 15 |
| 60% chance | Apr 11 |
| 70% chance | Apr 7 |
| 80% chance | Apr 3 |
| 90% chance | Mar 30 |
| Probability of hard freeze (20°F) on or after… | |
|---|---|
| 10% chance | Apr 20 |
| 20% chance | Apr 15 |
| 30% chance | Apr 10 |
| 40% chance | Apr 7 |
| 50% chance | Apr 4 |
| 60% chance | Apr 1 |
| 70% chance | Mar 28 |
| 80% chance | Mar 22 |
| 90% chance | Mar 16 |
| Probability of severe hard freeze (16°F) on or after… | |
|---|---|
| 10% chance | Apr 12 |
| 20% chance | Apr 5 |
| 30% chance | Apr 1 |
| 40% chance | Mar 29 |
| 50% chance | Mar 24 |
| 60% chance | Mar 19 |
| 70% chance | Mar 14 |
| 80% chance | Mar 8 |
| 90% chance | Mar 2 |
Agricultural climatic data from weather station: CANYON FERRY DAM (USC00241470)