Oroville, CA Frost Dates & Growing Season

The two dates every Oroville garden is planned around, plus ready-computed planting windows for the most popular crops.

Last spring frost
Jan 30
~50% chance of frost after
First fall frost
Dec 13
~50% chance of frost before
Growing season
317 days
frost-free stretch
USDA zone
≈ 9b
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Dec 26 Jan 30 Mar 3
First fall frost Jan 11 Dec 13 Nov 21
Hard freeze (28°F), median last Jan 5 · first Dec 25

Computed from NOAA 1991–2020 climate normals at the OROVILLE station. "Safe" means frost past that date happens only about one year in ten. Your exact garden can still run days either way with elevation and terrain — check your own ZIP with the frost date lookup.

Planting windows for Oroville

Computed from Oroville's own frost dates. Click any crop for the full zone-9 growing guide — varieties, spacing, fall plantings, and more.

CropStart seeds indoorsTransplantDirect sow
🍅 Tomatoes Dec 5 – Dec 19 Feb 6 – Feb 13
🫑 Peppers Nov 21 – Dec 5 Feb 13 – Feb 20
🥬 Lettuce Dec 19 – Jan 2 Jan 2 – Jan 16 Jan 2 – Jan 30
🫛 Peas Dec 19 – Jan 2
🥕 Carrots Jan 9 – Jan 30
🥦 Broccoli Dec 12 – Dec 26 Jan 9 – Jan 23
🥬 Kale Dec 19 – Jan 2 Jan 2 – Jan 16 Jan 2 – Jan 16
🥒 Cucumbers Jan 2 – Jan 9 Feb 6 – Feb 13 Feb 6 – Feb 13
🥒 Zucchini Jan 2 – Jan 9 Feb 6 – Feb 13 Feb 6 – Feb 13
🫘 Green Beans (Bush) Feb 6 – Feb 13
🌽 Sweet Corn Feb 6 – Feb 13
🌿 Basil Dec 19 – Jan 2 Feb 6 – Feb 13 Feb 13 – Feb 20
🧄 Garlic Fall: Nov 1 – Nov 29

Want this for all 50 crops, or as a printable seed-shelf schedule? Use the planting calendar and the seed starting scheduler — both can use Oroville's dates automatically after a lookup.

Reading the season in Oroville

With roughly 317 frost-free days, Oroville gardens fit long-season crops — melons, winter squash, sweet potatoes — with room left for spring and fall rounds of greens and roots. The first frost around Dec 13 is late enough that fall planting is a full second season, not an afterthought.

Frequently asked questions

When is the last frost in Oroville, CA?

The average last spring frost in Oroville is around Jan 30, based on 1991–2020 climate normals. That's a median — about half of years see a later frost, so tender crops are safest going out a week or two after this date.

When is the first frost in Oroville, CA?

The average first fall frost in Oroville arrives around Dec 13. Crops still in the garden need to mature before then, and frost-tender plants need harvesting or protection as the date approaches.

How long is the growing season in Oroville?

About 317 frost-free days on average, from Jan 30 to Dec 13. That comfortably fits long-season crops like melons and winter squash, plus spring and fall plantings of cool-season vegetables.

What USDA zone is Oroville in?

USDA zone 9b on the 2023 Plant Hardiness Zone Map. Note that zones describe winter cold, not frost timing — these frost dates are the numbers to plan plantings around.