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🍂 First Frost Dates for Hillsboro, Oregon 97123

The first 36°F frost date is 30% likely to be on Oct 18. (See detailed probabilities below.)

The first 32°F light freeze date is 30% likely to be on Nov 5. (See detailed probabilities below.)

(See also 🌷 Last Spring Frost Dates.)

First frost date probabilities for Hillsboro, OR 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 14
30% chanceOct 18
40% chanceOct 22
50% chanceOct 26
60% chanceOct 29
70% chanceNov 1
80% chanceNov 8
90% chanceNov 19
Probability of light freeze (32°F) on or before...
10% chanceOct 25
20% chanceNov 1
30% chanceNov 5
40% chanceNov 11
50% chanceNov 18
60% chanceNov 25
70% chanceDec 1
80% chanceDec 7
90% chanceDec 15
Probability of moderate freeze (28°F) on or before...
10% chanceNov 10
20% chanceNov 20
30% chanceNov 29
40% chanceDec 5
50% chanceDec 11
60% chanceDec 17
70% chanceDec 25
80% chanceJan 1
90% chanceJan 18
Probability of moderate hard freeze (24°F) on or before...
10% chanceNov 24
20% chanceDec 5
30% chanceDec 12
40% chanceDec 19
50% chanceDec 27
60% chanceJan 1
70% chanceJan 9
80% chanceJan 24
90% chanceFeb 4
Probability of hard freeze (20°F) on or before...
10% chanceDec 1
20% chanceDec 11
30% chanceDec 17
40% chanceDec 25
50% chanceDec 29
60% chanceJan 1
70% chanceJan 14
80% chanceFeb 1
90% chanceFeb 8
Probability of severe hard freeze (16°F) on or before...
10% chanceDec 7
20% chanceDec 13
30% chanceDec 18
40% chanceDec 23
50% chanceDec 27
60% chanceDec 30
70% chanceJan 1
80% chanceJan 17
90% chanceFeb 2

Agricultural climatic data from weather station: HILLSBORO (USC00353908)

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