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🍂 First Frost Dates for San Mateo, California 94403

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

The first 32°F light freeze date is 30% likely to be on Dec 3. (See detailed probabilities below.)

(See also 🌷 Last Spring Frost Dates.)

First frost date probabilities for San Mateo, CA 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% chanceNov 10
20% chanceNov 14
30% chanceNov 18
40% chanceNov 22
50% chanceNov 25
60% chanceNov 29
70% chanceDec 2
80% chanceDec 6
90% chanceDec 14
Probability of light freeze (32°F) on or before...
10% chanceNov 24
20% chanceDec 1
30% chanceDec 3
40% chanceDec 8
50% chanceDec 12
60% chanceDec 18
70% chanceDec 25
80% chanceJan 1
90% chanceJan 14
Probability of moderate freeze (28°F) on or before...
10% chanceDec 5
20% chanceDec 10
30% chanceDec 15
40% chanceDec 20
50% chanceDec 26
60% chanceDec 31
70% chanceJan 4
80% chanceJan 13
90% chanceJan 27
Probability of moderate hard freeze (24°F) on or before...
10% chancerarely
20% chancerarely
30% chancerarely
40% chancerarely
50% chancerarely
60% chancerarely
70% chancerarely
80% chancerarely
90% chancerarely
Probability of hard freeze (20°F) on or before...
10% chancerarely
20% chancerarely
30% chancerarely
40% chancerarely
50% chancerarely
60% chancerarely
70% chancerarely
80% chancerarely
90% chancerarely
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: REDWOOD CITY (USC00047339)

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