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🍂 First Frost Dates for Ismay, Montana 59336

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 5. (See detailed probabilities below.)

(See also 🌷 Last Spring Frost Dates.)

First frost date probabilities for Ismay, 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% chanceAug 29
20% chanceSep 2
30% chanceSep 5
40% chanceSep 8
50% chanceSep 11
60% chanceSep 13
70% chanceSep 16
80% chanceSep 19
90% chanceSep 24
Probability of moderate freeze (28°F) on or before...
10% chanceSep 6
20% chanceSep 11
30% chanceSep 14
40% chanceSep 17
50% chanceSep 19
60% chanceSep 22
70% chanceSep 25
80% chanceSep 28
90% chanceOct 2
Probability of moderate hard freeze (24°F) on or before...
10% chanceSep 14
20% chanceSep 19
30% chanceSep 22
40% chanceSep 25
50% chanceSep 28
60% chanceOct 1
70% chanceOct 3
80% chanceOct 6
90% chanceOct 10
Probability of hard freeze (20°F) on or before...
10% chanceSep 22
20% chanceSep 27
30% chanceOct 1
40% chanceOct 3
50% chanceOct 6
60% chanceOct 9
70% chanceOct 13
80% chanceOct 16
90% chanceOct 22
Probability of severe hard freeze (16°F) on or before...
10% chanceOct 1
20% chanceOct 6
30% chanceOct 11
40% chanceOct 15
50% chanceOct 18
60% chanceOct 21
70% chanceOct 24
80% chanceOct 28
90% chanceNov 2

Agricultural climatic data from weather station: MIZPAH 4 NNW (USC00245754)

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