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🍂 First Frost Dates for Harleysville, Pennsylvania 19438

The first 36°F frost date is 30% likely to be on Oct 13. (See detailed probabilities below.)

The first 32°F light freeze date is 30% likely to be on Oct 25. (See detailed probabilities below.)

(See also 🌷 Last Spring Frost Dates.)

First frost date probabilities for Harleysville, PA 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% chanceOct 6
20% chanceOct 9
30% chanceOct 13
40% chanceOct 16
50% chanceOct 18
60% chanceOct 21
70% chanceOct 25
80% chanceOct 29
90% chanceNov 3
Probability of light freeze (32°F) on or before...
10% chanceOct 16
20% chanceOct 21
30% chanceOct 25
40% chanceOct 28
50% chanceNov 1
60% chanceNov 3
70% chanceNov 6
80% chanceNov 10
90% chanceNov 16
Probability of moderate freeze (28°F) on or before...
10% chanceOct 29
20% chanceNov 3
30% chanceNov 7
40% chanceNov 11
50% chanceNov 15
60% chanceNov 18
70% chanceNov 22
80% chanceNov 27
90% chanceDec 2
Probability of moderate hard freeze (24°F) on or before...
10% chanceNov 13
20% chanceNov 18
30% chanceNov 23
40% chanceNov 27
50% chanceDec 1
60% chanceDec 3
70% chanceDec 7
80% chanceDec 11
90% chanceDec 16
Probability of hard freeze (20°F) on or before...
10% chanceNov 25
20% chanceDec 1
30% chanceDec 5
40% chanceDec 8
50% chanceDec 12
60% chanceDec 16
70% chanceDec 19
80% chanceDec 24
90% chanceDec 29
Probability of severe hard freeze (16°F) on or before...
10% chanceDec 5
20% chanceDec 11
30% chanceDec 16
40% chanceDec 20
50% chanceDec 25
60% chanceDec 28
70% chanceJan 1
80% chanceJan 7
90% chanceJan 18

Agricultural climatic data from weather station: GREEN LANE (USC00363488)

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