Beringer Brothers-Los Hermanos Winery · Photo: Frank Schulenburg · CC BY-SA 4.0Midwinter lows in St. Helena stay above those of 85% of U.S. towns
On a normal July day the thermometer tops out near 89°. Precipitation is light here, less than falls on 84% of U.S. towns. Since 1901–2000, the year has warmed by 1.6°, most of all in January. Long walks are most pleasant from March to May and October to November, when afternoons reach 66–79°.
A year in St. Helena at a glance
Each month’s typical high and low, and what it brings.
What stands out about St. Helena’s climate
Compared with towns across the U.S., with St. Helena’s place in California beside it.
What a year in St. Helena feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 306 frost-free days a year
In half of years the last 32° night comes by February 3 and the first by December 4. Frost and day counts come from NOAA’s station at Saint Helena, CA, 0.4 miles from the town’s center, at about the same height.
The 2023 USDA map puts St. Helena’s center in zone 9b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 25°. 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 32 inches of rain a year
December is the wettest month and July the driest. Rain falls on about 69 days a year. Snow is rare: about 0.0" in a normal year at Saint Helena, CA, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in St. Helena
72% 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 Saint Helena, CA.
Living with St. Helena’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
306 frost-free days in zone 9b. The last frost comes by Feb 3 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, October and November. 3.4 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in St. Helena from natural hazards, river flooding is the largest share (49%). Normals are averages; the hazards page covers the extremes.
Natural hazards →St. Helena and similar climates
TownRatings has no climate map of the towns around St. Helena yet.
Climates most like St. Helena’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 |
|---|---|---|---|---|
| St. Helena, CA | 38° | 89° | 32" | 0.0" |
| Grants Pass, OR | 34° | 90° | 33" | 0.9" |
| Boerne, TX | 39° | 93° | 33" | 0.1" |
| Camden, SC | 33° | 92° | 43" | 0.0" |
| Marvin, NC | 31° | 91° | 43" | 0.2" |
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 St. Helena averaged 1.6° warmer than the 1900s. The biggest change is in January (+2.5°).
A bigger shift than in 63% 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 St. Helena compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with St. Helena’s place among California’s.
St. Helena weather by month
Highs, lows and precipitation from NOAA’s grid at St. Helena’s center; snow, wet days and snow on the ground from Saint Helena, CA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 58° | 38° | 6.6" | 0.0" | 13 | 0 | 44° – 54° |
| February | 62° | 40° | 6.3" | 0.0" | 11 | 0 | 46° – 57° |
| March | 67° | 41° | 4.5" | 0.0" | 10 | 0 | 47° – 61° |
| April | 71° | 44° | 1.9" | 0.0" | 6 | 0 | 51° – 62° |
| May | 78° | 48° | 1.0" | 0.0" | 3 | 0 | 56° – 70° |
| June | 85° | 52° | 0.2" | 0.0" | 1 | 0 | 65° – 72° |
| July | 89° | 54° | 0.0" | 0.0" | 0 | 0 | 69° – 75° |
| August | 89° | 54° | 0.0" | 0.0" | 0 | 0 | 68° – 75° |
| September | 87° | 51° | 0.1" | 0.0" | 1 | 0 | 66° – 72° |
| October | 79° | 47° | 1.5" | 0.0" | 3 | 0 | 60° – 69° |
| November | 66° | 41° | 3.2" | 0.0" | 8 | 0 | 46° – 58° |
| December | 57° | 37° | 6.6" | 0.0" | 13 | 0 | 43° – 51° |
| Year | 74° | 46° | 31.8" | 0.0" | 69 | 0 |
How much a month can swing
A normal is an average. May swings the most: from 1991 to 2020 its average ranged from 56° to 70°. September is the most reliable, staying within 6°.
Where St. Helena’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 St. Helena’s center.
- Snow: Saint Helena, CA (NOAA station in town).
- Frost, freezing nights, 90° and 100° days, heating and cooling: Saint Helena, CA, 0.4 miles from the town’s center, 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 St. Helena’s climate
What is the weather like in St. Helena?
A typical July afternoon reaches 89°, a January night drops to 38°, and snow is almost unheard of. Milder January nights than 85% of U.S. towns; hotter July afternoons than 73% of U.S. towns.
How cold does it get in St. Helena in winter?
December nights average 37°. About 14 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 43°.
How much snow does St. Helena get?
About 0.0 inches in a normal winter at Saint Helena, CA, so most winters see none.
How hot does it get in St. Helena?
July, with a typical high of 89° and a low of 54°. About 55 days a year reach 90° and 9 reach 100° (Saint Helena, CA).
When is the first and last frost in St. Helena?
In half of years the last spring frost (32°) comes by February 3 and the first fall frost by December 4, about 306 frost-free days, at Saint Helena, CA.
What growing zone is St. Helena in?
Zone 9b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 25°.
What is the best time of year to visit St. Helena?
By one simple rule (highs of 62–84° and lows of 40° or more), March, April, May, October and November. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is St. Helena getting warmer?
Yes: 1991–2020 averaged 1.6° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 63% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in St. Helena.
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.