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🍂 First Frost Dates for San Tan Valley, Arizona 85143

The first 36°F frost date is 30% likely to be on Nov 9. (See detailed probabilities below.)

The first 32°F light freeze date is 30% likely to be on Nov 19. (See detailed probabilities below.)

(See also 🌷 Last Spring Frost Dates.)

First frost date probabilities for San Tan Valley, AZ 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 30
20% chanceNov 5
30% chanceNov 9
40% chanceNov 12
50% chanceNov 15
60% chanceNov 18
70% chanceNov 20
80% chanceNov 24
90% chanceNov 29
Probability of light freeze (32°F) on or before...
10% chanceNov 11
20% chanceNov 16
30% chanceNov 19
40% chanceNov 22
50% chanceNov 26
60% chanceNov 29
70% chanceDec 2
80% chanceDec 5
90% chanceDec 11
Probability of moderate freeze (28°F) on or before...
10% chanceNov 21
20% chanceNov 27
30% chanceDec 1
40% chanceDec 5
50% chanceDec 9
60% chanceDec 13
70% chanceDec 18
80% chanceDec 24
90% chanceJan 3
Probability of moderate hard freeze (24°F) on or before...
10% chanceNov 30
20% chanceDec 8
30% chanceDec 14
40% chanceDec 21
50% chanceDec 27
60% chanceJan 1
70% chanceJan 6
80% chanceJan 16
90% chanceJan 29
Probability of hard freeze (20°F) on or before...
10% chanceDec 15
20% chanceDec 25
30% chanceDec 29
40% chanceJan 1
50% chanceJan 4
60% chanceJan 7
70% chanceJan 11
80% chanceJan 18
90% chanceJan 28
Probability of severe hard freeze (16°F) on or before...
10% chancerarely
20% chancerarely
30% chancerarely
40% chancerarely
50% chancerarely
60% chancerarely
70% chancerarely
80% chancerarely
90% chancerarely

Agricultural climatic data from weather station: CASA GRANDE NM (USC00021314)

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