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🍂 First Frost Dates for Hartline, Washington 99135

The first 36°F frost date is 30% likely to be on Sep 20. (See detailed probabilities below.)

The first 32°F light freeze date is 30% likely to be on Oct 1. (See detailed probabilities below.)

(See also 🌷 Last Spring Frost Dates.)

First frost date probabilities for Hartline, WA 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 9
20% chanceSep 15
30% chanceSep 20
40% chanceSep 24
50% chanceSep 28
60% chanceOct 1
70% chanceOct 3
80% chanceOct 6
90% chanceOct 11
Probability of light freeze (32°F) on or before...
10% chanceSep 23
20% chanceSep 29
30% chanceOct 1
40% chanceOct 5
50% chanceOct 8
60% chanceOct 11
70% chanceOct 15
80% chanceOct 18
90% chanceOct 24
Probability of moderate freeze (28°F) on or before...
10% chanceOct 5
20% chanceOct 10
30% chanceOct 15
40% chanceOct 19
50% chanceOct 22
60% chanceOct 25
70% chanceOct 28
80% chanceNov 1
90% chanceNov 6
Probability of moderate hard freeze (24°F) on or before...
10% chanceOct 17
20% chanceOct 23
30% chanceOct 27
40% chanceOct 30
50% chanceNov 2
60% chanceNov 5
70% chanceNov 10
80% chanceNov 14
90% chanceNov 20
Probability of hard freeze (20°F) on or before...
10% chanceOct 25
20% chanceNov 1
30% chanceNov 5
40% chanceNov 10
50% chanceNov 14
60% chanceNov 18
70% chanceNov 23
80% chanceNov 29
90% chanceDec 5
Probability of severe hard freeze (16°F) on or before...
10% chanceNov 3
20% chanceNov 12
30% chanceNov 17
40% chanceNov 23
50% chanceNov 28
60% chanceDec 2
70% chanceDec 7
80% chanceDec 13
90% chanceDec 22

Agricultural climatic data from weather station: HARTLINE (USC00453529)

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