Frost dates for Hayward, California

Hayward doesn't get a freezing night every winter: about 45 years in 100 have one. In those years, half have had their last frost by January 2 and half their first by December 25.

Stations near you disagree. NOAA's Hayward Air Terminal (2 miles away, at 40 feet above sea level), the one we used, gives a typical last frost of January 2 and a typical first frost of December 25. NOAA's Redwood City (15 miles away, at 30 feet above sea level) gives a typical last frost of January 17 and a typical first frost of December 12. So the typical last frost could fall anywhere from January 2 to 17 and the typical first frost from December 12 to 25, depending on whether your garden is more like one or the other. Local terrain matters: hillsides, valley floors, water and city heat can change frost dates a lot over a few miles. Treat the dates here as a starting point, and compare with a nearby gardener or your county extension office.

Print a year planner for Hayward

Frost risk through the year

JanJFebFMarMAprAMayMJunJJulJAugASepSOctONovNDecD

How sure are these dates?

A frost date is a probability, not a promise. NOAA worked out, from 30 years of nightly lows, how often the last spring frost and the first fall frost fall on each date. The middle column is the typical year. The outer columns are the early and late years that come about once a decade.

In a typical year there is no freezing night at all. In 1 year in 10, the longest frost-free stretch is 338 days or shorter.

• Frost possible (36°F at the station): about 93 years in 100 have one. In those years the last typically comes on January 29 and the first on December 12. On clear, still nights the ground can be several degrees colder than the thermometer, so frost can form on plants when the official reading is in the mid-30s.

Planting calendar for Hayward

These dates count from the typical last and first frosts, using the planting rules published by Colorado State University Extension (spring), Virginia Cooperative Extension (fall crops) and University of Minnesota Extension (garlic, where winters are hard). Weather in any one year can run early or late, so check the forecast before you plant tender crops.

Frost comes in fewer than half of years here (about 45 years in 100), so we don't build a planting calendar around it: in most years there is no last frost to plant after. Your county's extension office publishes planting dates made for your climate.

For spring bulbs such as tulips and daffodils, plant once the soil has cooled to about 50 to 55°F and keep going until a couple of weeks before the ground freezes. Our guide to fall planting explains how to tell.

Where these numbers come from

These dates come from NOAA's weather station Hayward Air Terminal (station USW00093228), 2 miles from the center of Hayward. It sits at about the same elevation, 40 feet above sea level. NOAA rates this station's record as representative: at least 10 of the 30 years, with the gaps filled from nearby stations.

The same station also gives the frost dates for Union City.

Our ZIP code lookup matches these 9 ZIP codes to the same station, so they get the same dates: 94541, 94542, 94544, 94545, 94546, 94578, 94579, 94580, 94605. Hardiness zones are worked out separately for each ZIP code.

Nearby places

• Fremont, California: frost not every year (15 miles away)
• Concord, California: frost not every year (25 miles away)
• Richmond, California: frost not every year (25 miles away)

See frost dates across California, or look up your own ZIP code for the station nearest you. Want the background? Read what a last frost date really means.