When is the last frost in Napa, CA?

The average last spring frost (50% probability of 32°F) in Napa is around March 6, based on NOAA/NCEI 1991–2020 normals at the Markley Cove, CA station (7.9 mi away). Half of years it falls outside that date, so wait 1–2 weeks past it before setting out frost-tender plants.

When is the first fall frost in Napa?

The average first fall frost in Napa, CA is around November 30, giving roughly a 266-day frost-free growing season.

What planting zone is Napa, CA?

Napa is in USDA plant hardiness zone 9b (average annual extreme minimum temperature 25 to 30°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in Napa?

In Napa, CA the warmest month is July (avg high 94.8°F) and the coldest is January (avg low 36.4°F). It averages about 28″ of precipitation a year.

Home › California › Napa

Napa, CA Planting Calendar & Frost Dates

USDA hardiness zone 9b · ZIP 94558 · elevation 146′ · NOAA & USDA data

Napa is in USDA hardiness zone 9b (winters can dip to 25 to 30°F), with a growing season of about 266 days between the average last spring frost (March 6) and first fall frost (November 30). The warmest month is July (avg high 94.8°F); the coldest is January (avg low 36.4°F). It averages 28″ of precipitation a year. Start cool-season crops several weeks before the last frost; wait until after it for tomatoes, peppers and other tender crops.

Hardiness zone

min temp 25 to 30°F

Last spring frost

March 6

avg (50% prob, 32°F)

First fall frost

November 30

avg (50% prob, 32°F)

Growing season

266 days

frost-free window

Warmest month

July

avg high 94.8°F

Month-by-month typical weather in Napa

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Markley Cove, CA (7.9 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)
January	57.4	36.4	46.9	5.7
February	61.4	37.9	49.6	5.9
March	66	40.2	53.1	4.1
April	71.3	42.9	57.1	1.7
May	79.3	48.5	63.9	1
June	88	54.1	71	0.2
July	94.8	56.8	75.8	0
August	94.1	55.8	75	0
September	90.1	53.3	71.7	0.1
October	79.4	47.3	63.4	1.1
November	66.1	40.6	53.3	2.5
December	57.5	36.4	46.9	5.6

What to plant when in Napa

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: January 23 · Transplant out: March 13
Peppers	warm	Start seeds indoors: January 9 · Transplant out: March 20
Cucumbers	warm	Direct sow: March 13
Zucchini / squash	warm	Direct sow: March 13
Bush beans	warm	Direct sow: March 13
Sweet corn	warm	Direct sow: March 13
Basil	warm	Transplant out: March 13
Peas	cool	Sow (spring): January 30 · Sow (fall): October 5
Spinach	cool	Sow (spring): January 23 · Sow (fall): October 5
Lettuce	cool	Sow (spring): February 6 · Sow (fall): October 5
Kale	cool	Transplant (spring): February 13 · Sow (fall): September 21
Broccoli	cool	Transplant (spring): February 20
Carrots	cool	Sow (spring): February 13 · Sow (fall): September 21
Onions	cool	Transplant (spring): February 6
Potatoes	cool	Plant seed potatoes: February 20
Radishes	cool	Sow (spring): February 6 · Sow (fall): October 19

Dates are computed from Napa's average frost dates using standard cool-/warm-season timing. They're a starting point — a cold spring, a warm microclimate, or a fast-maturing variety can shift them by a week or two.

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Gear that helps you plant on time

Some links below are Amazon affiliate links (tag theboringthin-20). If you buy through them we may earn a small commission at no extra cost to you — it keeps this almanac free. We only list generic, genuinely-useful categories.

Soil thermometer →Know when the ground is warm enough to sow — the honest signal, not the calendar.Seed-starting trays + dome →Start tomatoes & peppers indoors on the schedule below.Seedling heat mat →Warms the soil for faster, more even germination indoors.Floating row cover / frost cloth →Buys you 4–8°F to beat an early or late frost.Raised garden bed kit →Warms and drains faster in spring than in-ground soil.Garden gloves →Basic kit for transplant day.

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Sources & method. Hardiness zone: 2023 USDA Plant Hardiness Zone Map (PRISM Climate Group, Oregon State University). Frost dates & growing season: NOAA/NCEI 1991–2020 U.S. Climate Normals, nearest station with published freeze normals — Markley Cove, CA, 7.9 mi (confidence: high). Monthly weather normals: Markley Cove, CA, 7.9 mi (confidence: high). ZIP centroid from U.S. Census 2023 ZCTA data. Frost dates are the 50%-probability date — half of years frost occurs outside the stated date. Nothing here is invented; where the nearest station is far, we say so. Last updated 2026-07-22.