Photo: Oleg Alexandrov · CC BY-SA 4.0Napa’s winters are milder and less snowy than most of the U.S.
A typical July afternoon reaches 86°, a January night drops to 38°, and snow is almost unheard of.
A year in Napa at a glance
Each month’s typical high and low, and what it brings.
What stands out about Napa’s climate
Compared with towns across the U.S., with Napa’s place in California beside it.
What a year in Napa feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 299 frost-free days a year
In half of years the last 32° night comes by February 12 and the first by December 4. Frost and day counts come from NOAA’s station at Napa State Hospital, CA, 2.4 miles from the city’s center point, at about the same height.
The 2023 USDA map puts Napa’s center in zone 9b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 26°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 26 inches of rain a year
December is the wettest month and July the driest. Rain falls on about 68 days a year. Snow is rare: about 0.0" in a normal year at Napa State Hospital, CA, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Napa
79% of the work is heating. Months averaging under 55° run from November through March.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Napa State Hospital, CA.
Living with Napa’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
299 frost-free days in zone 9b. The last frost comes by Feb 12 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Dec 4.
Months with highs of 62–84° and lows of 40° or more: March, April, May, June, October and November. 20 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Napa from natural hazards, river flooding is the largest share (54%); heat waves, cold waves, winter storms and ice storms together are 1%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Napa and similar climates
TownRatings has no climate map of the towns around Napa yet.
Climates most like Napa’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Napa, CA | 38° | 86° | 26" | 0.0" |
| Green, OR | 37° | 86° | 32" | 0.0" |
| Sierra Vista Southeast, AZ | 32° | 91° | 15" | 0.7" |
| Aransas Pass, TX | 49° | 91° | 34" | 0.3" |
| Felida, WA | 35° | 81° | 42" | 0.8" |
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in Napa averaged 1.6° warmer than the 1900s. The biggest change is in January (+2.1°).
A bigger shift than in 66% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Napa compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Napa’s place among California’s.
Napa weather by month
Highs, lows and precipitation from NOAA’s grid at Napa’s center; snow, wet days and snow on the ground from Napa State Hospital, CA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 57° | 38° | 5.2" | 0.0" | 12 | 0 | 44° – 51° |
| February | 62° | 41° | 5.1" | 0.0" | 11 | 0 | 47° – 55° |
| March | 66° | 42° | 3.7" | 0.0" | 10 | 0 | 49° – 60° |
| April | 71° | 45° | 1.7" | 0.0" | 7 | 0 | 53° – 62° |
| May | 76° | 49° | 0.9" | 0.0" | 4 | 0 | 57° – 68° |
| June | 83° | 53° | 0.2" | 0.0" | 1 | 0 | 64° – 70° |
| July | 86° | 55° | 0.0" | 0.0" | 0 | 0 | 67° – 74° |
| August | 86° | 54° | 0.1" | 0.0" | 0 | 0 | 67° – 74° |
| September | 85° | 52° | 0.1" | 0.0" | 1 | 0 | 65° – 72° |
| October | 78° | 48° | 1.3" | 0.0" | 4 | 0 | 60° – 68° |
| November | 66° | 42° | 2.7" | 0.0" | 8 | 0 | 48° – 58° |
| December | 57° | 38° | 5.4" | 0.0" | 12 | 0 | 44° – 52° |
| Year | 73° | 46° | 26.3" | 0.0" | 68 | 0 |
How much a month can swing
A normal is an average. March swings the most: from 1991 to 2020 its average ranged from 49° to 60°. June is the most reliable, staying within 6°.
Where Napa’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Napa’s center.
- Snow: Napa State Hospital, CA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Napa State Hospital, CA, 2.4 miles from the city’s center point, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Napa’s climate
What is the weather like in Napa?
A typical July afternoon reaches 86°, a January night drops to 38°, and snow is almost unheard of. Milder January nights than 86% of U.S. towns; hotter July afternoons than 54% of U.S. towns.
How cold does it get in Napa in winter?
December nights average 38°. About 13 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 44°.
How much snow does Napa get?
About 0.0 inches in a normal winter at Napa State Hospital, CA, so most winters see none.
How hot does it get in Napa?
July, with a typical high of 86° and a low of 55°. About 32 days a year reach 90° and 5 reach 100° (Napa State Hospital, CA).
When is the first and last frost in Napa?
In half of years the last spring frost (32°) comes by February 12 and the first fall frost by December 4, about 299 frost-free days, at Napa State Hospital, CA.
What growing zone is Napa in?
Zone 9b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 26°.
What is the best time of year to visit Napa?
By one simple rule (highs of 62–84° and lows of 40° or more), March, April, May, June, October and November. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Napa getting warmer?
Yes: 1991–2020 averaged 1.6° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 66% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Napa.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.