When to plant in Riverside, CA
USDA Zone 10aEverything below — frost dates, hardiness zone, and what to plant when in Riverside, California — is derived from the closest NOAA station with complete climate normals.
Riverside enjoys a long ~350-day frost-free season — you can succession-sow, fit in a second crop, and grow long-season heat-lovers with room to spare. In zone 10a, frost is a minor factor for Riverside — most perennials thrive, and annual vegetables can go out early and stay late.
Frost probability
RIVERSIDE FIRE STN 3 · 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 Riverside’s own odds, recorded at RIVERSIDE FIRE STN 3.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Mar 22 | Feb 19 | Jan 8 | Nov 15 | Dec 6 | Jan 1 |
| 32°F | Feb 25 | Jan 9 | Dec 16 | Dec 1 | Dec 25 | Jan 27 |
| 28°F | Jan 16 | Dec 31 | Dec 13 | Nov 30 | Dec 29 | 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 Riverside, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 4 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.
Riverside planting FAQ
When is the last spring frost in Riverside, CA?
On average, the last spring frost in Riverside is around January 9 (50% probability at 32°F, from 1991–2020 NOAA normals). Wait until after this date to set out tender plants like tomatoes and peppers.
When is the first fall frost in Riverside, CA?
The first fall frost in Riverside typically arrives around December 25 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Riverside in?
Riverside is in USDA hardiness zone 10a. In zone 10a, winters are mild — many tender perennials overwinter here.
How long is the growing season in Riverside?
Riverside has about 350 frost-free days — a long growing season — between the average last spring frost (January 9) and first fall frost (December 25).
When should I plant tomatoes in Riverside?
For Riverside, sow tomatoes indoors about November 14–November 28 and move the seedlings out around January 16, after the last spring frost.
Never miss a window in Riverside
An email when it’s time to start seeds, transplant, and sow — timed to Riverside’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Woodcrest · 7 km
- Jurupa Valley · 10 km
- Grand Terrace · 13 km
- Home Gardens · 13 km
- Bloomington · 14 km
- Colton · 14 km
- Norco · 15 km
- Mead Valley · 15 km
Frost dates recorded at RIVERSIDE FIRE STN 3, 2 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 Riverside, CA — Frost Dates & Zone 10a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00047470. Retrieved from https://blissgarden.com/california/riverside.