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🍂 First Frost Dates for Ronan, Montana 59864

The first 36°F frost date is 30% likely to be on Sep 15. (See detailed probabilities below.)

The first 32°F light freeze date is 30% likely to be on Sep 27. (See detailed probabilities below.)

(See also 🌷 Last Spring Frost Dates.)

First frost date probabilities for Ronan, 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% chanceSep 7
20% chanceSep 12
30% chanceSep 15
40% chanceSep 19
50% chanceSep 22
60% chanceSep 25
70% chanceSep 28
80% chanceOct 1
90% chanceOct 5
Probability of light freeze (32°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 freeze (28°F) on or before...
10% chanceSep 27
20% chanceOct 2
30% chanceOct 6
40% chanceOct 9
50% chanceOct 13
60% chanceOct 16
70% chanceOct 19
80% chanceOct 23
90% chanceOct 29
Probability of moderate hard freeze (24°F) on or before...
10% chanceOct 6
20% chanceOct 14
30% chanceOct 19
40% chanceOct 22
50% chanceOct 26
60% chanceOct 30
70% chanceNov 2
80% chanceNov 6
90% chanceNov 12
Probability of hard freeze (20°F) on or before...
10% chanceOct 19
20% chanceOct 27
30% chanceNov 1
40% chanceNov 4
50% chanceNov 8
60% chanceNov 11
70% chanceNov 15
80% chanceNov 21
90% chanceNov 27
Probability of severe hard freeze (16°F) on or before...
10% chanceOct 30
20% chanceNov 5
30% chanceNov 10
40% chanceNov 15
50% chanceNov 21
60% chanceNov 25
70% chanceNov 29
80% chanceDec 4
90% chanceDec 12

Agricultural climatic data from weather station: POLSON (USC00246635)

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