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🍂 First Frost Dates for Thompson, Iowa 50478

The first 36°F frost date is 30% likely to be on Sep 21. (See detailed probabilities below.)

The first 32°F light freeze date is 30% likely to be on Sep 29. (See detailed probabilities below.)

(See also 🌷 Last Spring Frost Dates.)

First frost date probabilities for Thompson, IA 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 15
20% chanceSep 19
30% chanceSep 21
40% chanceSep 24
50% chanceSep 26
60% chanceSep 28
70% chanceSep 30
80% chanceOct 3
90% chanceOct 8
Probability of light freeze (32°F) on or before...
10% chanceSep 21
20% chanceSep 26
30% chanceSep 29
40% chanceOct 1
50% chanceOct 4
60% chanceOct 7
70% chanceOct 10
80% chanceOct 14
90% chanceOct 19
Probability of moderate freeze (28°F) on or before...
10% chanceOct 1
20% chanceOct 5
30% chanceOct 9
40% chanceOct 13
50% chanceOct 16
60% chanceOct 19
70% chanceOct 22
80% chanceOct 25
90% chanceOct 30
Probability of moderate hard freeze (24°F) on or before...
10% chanceOct 11
20% chanceOct 16
30% chanceOct 20
40% chanceOct 23
50% chanceOct 26
60% chanceOct 29
70% chanceNov 1
80% chanceNov 4
90% chanceNov 9
Probability of hard freeze (20°F) on or before...
10% chanceOct 21
20% chanceOct 26
30% chanceOct 30
40% chanceNov 1
50% chanceNov 4
60% chanceNov 7
70% chanceNov 10
80% chanceNov 14
90% chanceNov 18
Probability of severe hard freeze (16°F) on or before...
10% chanceNov 1
20% chanceNov 4
30% chanceNov 7
40% chanceNov 10
50% chanceNov 13
60% chanceNov 16
70% chanceNov 19
80% chanceNov 23
90% chanceNov 28

Agricultural climatic data from weather station: FOREST CITY 2 NNE (USC00132977)

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