Riverside frost dates and planting season

Name: Riverside
Address: California, United States

When to plant vegetables here. Cover calendars (fleece, cold frame, unheated greenhouse) are on each plant’s when-to-plant page.

Riverside frost dates are provisional (1 usable winters in this archive; not a 30-year normal yet). Plant cool-season crops after about October 19; wait until about April 20 for warm-season crops.

Frost-free days—Provisional — need 30-year archive

Cover calendars (fleece, cold frame, unheated greenhouse) live on each crop’s when-to-plant page.

Weekly possible temperature29 – 114 °F

Frost-free daysNot yet (short archive)

Typical last spring frostFebruary 5

Days suitable for warm-season vegetables126 (April 20 – June 28; September 14 – November 8)

Days suitable for cool-season vegetables225 (October 19 – May 31 (continues into next year))

Calculated by Plan & Plant · Method · Data 2019–2026

Frost and suitability dates are typical figures from climate statistics. Microclimates vary; they are not a guarantee.

Frost dates calculated by Plan & Plant from Weather data by Open-Meteo.com (CC BY 4.0). Local frost pockets, valleys and coastal sites can differ by 1–3 weeks.

How we calculated this

Data: ERA5-Land via Open-Meteo, cell 33.95, -117.40, years 2019–2026 (not a 30-year climate normal yet).
Typical and safer dates: Typical last frost is the date after which half of winters in this sample had no more frost; safer is later in the sample so fewer winters still frosted.
Confidence: Provisional — short or thin sample for this place.
Full methodology (algorithm 2026-10-season-6).

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What to plant when

Cool-season vegetables

Earliest outdoor start: October 19

Suitable window: October 19 – May 31 (continues into next year)

Cool-season crops prefer cooler weather.

See cool-season details

Warm-season vegetables

Earliest outdoor start: April 20

Suitable window: April 20 – June 28; September 14 – November 8

Warm-season crops need mild or warm weather and cannot take frost.

Frost kills these crops, and cold snaps set them back.

See warm-season details

Green = usually good weeks to grow; blue or gray = usually too cold for that crop type.

Starter plants for Riverside

Cool-season

Radish Sow: December 25 – May 4 Planting dates
Arugula Sow: December 25 – May 4 Planting dates
Spinach Sow: December 25 – May 4 Planting dates
Lettuce Sow: December 25 – May 4 Planting dates
Kale Sow: December 25 – February 18 Planting dates
Beet Sow: January 8 – July 31 Planting dates

Warm-season

Zucchini Sow: April 24 – June 18 Planting dates
Cucumber Sow: April 24 – June 18 Planting dates
Green bean Sow: April 14 – July 31 Planting dates
Tomato Transplant: April 14 – June 8 Start indoors, then transplant. Planting dates
Bell pepper Transplant: April 24 – June 18 Start indoors, then transplant. Planting dates

How these dates are judged

Last frost: The typical last spring date when frost is still expected.
First frost: The typical first fall date when frost returns.
Frost-free days: The approximate days between those two dates.
Cool-season vegetables: Crops that prefer cooler weather, such as lettuce, kale, peas, and radish.
Warm-season vegetables: Crops that need warm weather and cannot take frost, such as tomato, pepper, squash, and beans.

Cool-season planting window

Oct 19 – May 31 (225 days)

Warm-season planting window

Apr 20 – Jun 28; Sep 14 – Nov 8 (126 days)

Weekly temperatures and planting windows

Temperatures across the year for Riverside, with cool- and warm-season weeks and frost dates.

Possible min to max
Average min to max
Suitable
Tolerable
Too cold
Too hot

Selected week · tap a week or use the arrows

Week 43 · Oct 19 – Oct 25

Average 55 to 80 °F · Possible 45 to 96 °F

Cool season: tolerable

Warm season: tolerable

A week is suitable for a crop type when its average low and high sit inside that type's range and its possible readings stay within the frost and heat limits (cool: 28 °F to 81 °F, warm: 32 °F to 90 °F); crossing a limit makes it tolerable, and for warm crops any chance of frost makes it too cold.

Based on average frost dates.

California, United States · 33.95335, -117.39616 · 2026

Coldest weekly possible temperature29 °F

Hottest weekly possible temperature114 °F

Last expected spring frostFebruary 5

First expected fall frost

Show all 53 weeks