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🍂 First Frost Dates for Riley, Oregon 97758

A 36°F frost is always a risk here. (See detailed probabilities below.)

A 32°F light freeze is always a risk here. (See detailed probabilities below.)

(See also 🌷 Last Spring Frost Dates.)

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

Agricultural climatic data from weather station: SQUAW BUTTE-NORTHERN GREAT BAS (USC00358029)

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