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🍂 First Frost Dates for Sweet Grass, Montana 59484

A 36°F frost is always a risk here. (See detailed probabilities below.)

The first 32°F light freeze date is 30% likely to be on Sep 15. (See detailed probabilities below.)

(See also 🌷 Last Spring Frost Dates.)

First frost date probabilities for Sweet Grass, MT are based on historical climate data.

Always check your local forecast for the most up-to-date frost warnings.

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What is a First Frost Date?

The first fall frost signals the end of your local growing season. This date serves as an important deadline for gardeners and farmers. You'll need to complete harvesting before this point. Annuals and other tender plants will die back when frost hits, and perennial plants will enter their dormant phase for winter. Meanwhile, it's time to enjoy a cup of hot cocoa and a cozy sweater—and start planning your spring garden!

How to use the First Frost Date?

Watch your local weather forecasts in early fall to predict the first frost date. Harvest tender crops and protect vulnerable plants before frost arrives. For late-summer plantings, count backward from your area's average first frost date. This ensures your crops have enough time to mature. Keep track of when frost actually occurs in your garden each year. This helps you identify protected spots where the growing season might last longer.

First Frost Date Probabilities

Probability of frost (36°F) on or before...
10% chancealways
20% chancealways
30% chancealways
40% chancealways
50% chancealways
60% chancealways
70% chancealways
80% chancealways
90% chancealways
Probability of light freeze (32°F) on or before...
10% chanceSep 6
20% chanceSep 12
30% chanceSep 15
40% chanceSep 19
50% chanceSep 22
60% chanceSep 24
70% chanceSep 27
80% chanceOct 1
90% chanceOct 5
Probability of moderate freeze (28°F) on or before...
10% chanceSep 18
20% chanceSep 23
30% chanceSep 27
40% chanceSep 30
50% chanceOct 2
60% chanceOct 4
70% chanceOct 7
80% chanceOct 11
90% chanceOct 16
Probability of moderate hard freeze (24°F) on or before...
10% chanceSep 28
20% chanceOct 1
30% chanceOct 4
40% chanceOct 8
50% chanceOct 12
60% chanceOct 15
70% chanceOct 18
80% chanceOct 22
90% chanceOct 27
Probability of hard freeze (20°F) on or before...
10% chanceOct 5
20% chanceOct 11
30% chanceOct 16
40% chanceOct 19
50% chanceOct 22
60% chanceOct 26
70% chanceOct 29
80% chanceNov 2
90% chanceNov 8
Probability of severe hard freeze (16°F) on or before...
10% chanceOct 14
20% chanceOct 19
30% chanceOct 24
40% chanceOct 27
50% chanceOct 30
60% chanceNov 2
70% chanceNov 6
80% chanceNov 11
90% chanceNov 18

Agricultural climatic data from weather station: SUNBURST 8 E (USC00247996)

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