When to plant in San Mateo, CA
USDA Zone 10aEverything below — frost dates, hardiness zone, and what to plant when in San Mateo, California — is derived from the closest NOAA station with complete climate normals.
A ~-3-day frost-free window makes San Mateo a short-season garden: choose early varieties and start long-season crops indoors well ahead of the last frost. Zone 10a is warm enough that San Mateo can grow subtropical perennials, and the short (or absent) frost period barely limits the annual calendar.
The average first fall frost in San Mateo is now 5 days earlier than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
SAN FRANCISCO INTL AP · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are San Mateo’s own odds, recorded at SAN FRANCISCO INTL AP.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Feb 14 | Jan 8 | Dec 16 | Dec 5 | Dec 24 | Jan 24 |
| 32°F | Jan 13 | Dec 29 | Dec 11 | Dec 11 | Dec 26 | Jan 13 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Nothing new to sow or transplant outdoors in the next few weeks — a seasonal lull. Check the full-year calendar below for the next window.
Full-year planting calendar
Each bar is the exact window to take a planting action in San Mateo, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 15 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
San Mateo planting FAQ
When is the last spring frost in San Mateo, CA?
Plan for the last spring frost in San Mateo around December 29 (the date it has a 50% chance of a 32°F freeze). Anything frost-sensitive should go out after it.
When is the first fall frost in San Mateo, CA?
In San Mateo, the first 32°F freeze of fall lands around December 26 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is San Mateo in?
San Mateo is in USDA hardiness zone 10a. In zone 10a, winters are mild — many tender perennials overwinter here.
How long is the growing season in San Mateo?
There are roughly -3 frost-free days in San Mateo (a short growing season), running from the average last frost around December 29 to the first fall frost near December 26.
When should I plant tomatoes in San Mateo?
In San Mateo, start tomato seeds indoors around November 3–November 17, then transplant seedlings outdoors around January 5 once the danger of frost has passed.
Never miss a window in San Mateo
An email when it’s time to start seeds, transplant, and sow — timed to San Mateo’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Hillsborough · 4 km
- Foster City · 5 km
- Belmont · 5 km
- Burlingame · 6 km
- San Carlos · 8 km
- Millbrae · 9 km
- Redwood City · 10 km
- South San Francisco · 12 km
Frost dates recorded at SAN FRANCISCO INTL AP, 8 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in San Mateo, CA — Frost Dates & Zone 10a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USW00023234. Retrieved from https://blissgarden.com/california/san-mateo.