Diablo Grande is drier than 93% of U.S. towns: 15 inches of precipitation a year
The coldest hours of a January night bottom out at 39° on average. In January, nights here are milder than in 88% of U.S. towns. Decade by decade the climate has edged up, 1.6° above 1901–2000. The heating season runs December to February: each of those months averages under 50°.
A year in Diablo Grande at a glance
Each month’s typical high and low, and what it brings.
What stands out about Diablo Grande’s climate
Compared with towns across the U.S., with Diablo Grande’s place in California beside it.
What a year in Diablo Grande feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 312 frost-free days a year
In half of years the last 32° night comes by January 31 and the first by December 5. Frost dates and degree days from Modesto City Co Airport, 23 miles away.
The 2023 USDA map puts Diablo Grande’s center in zone 9b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 29°. 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 15 inches of rain a year
February is the wettest month and July the driest. Rain falls on about 57 days a year. Snow is rare: about 0.0" in a normal year at Turlock #2, CA, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Diablo Grande
59% 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 Modesto City Co Airport.
Living with Diablo Grande’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
312 frost-free days in zone 9b. The last frost comes by Jan 31 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 5.
Months with highs of 62–84° and lows of 40° or more: March, April, May, June, October and November. 1.0 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Diablo Grande from natural hazards, drought is the largest share (63%); heat waves, cold waves, winter storms and ice storms together are 1%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Diablo Grande and similar climates
TownRatings has no climate map of the towns around Diablo Grande yet.
Climates most like Diablo Grande’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 |
|---|---|---|---|---|
| Diablo Grande, CA | 39° | 90° | 15" | 0.0" |
| Sierra Vista Southeast, AZ | 32° | 91° | 15" | 0.7" |
| Ashland, OR | 31° | 91° | 19" | 0.5" |
| Alpine, TX | 30° | 90° | 15" | 2.2" |
| Finley, WA | 29° | 91° | 9" | 2.0" |
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 Diablo Grande averaged 1.6° warmer than the 1900s. The biggest change is in January (+2.2°).
A bigger shift than in 68% 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 Diablo Grande compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Diablo Grande’s place among California’s.
Diablo Grande weather by month
Highs, lows and precipitation from NOAA’s grid at Diablo Grande’s center; snow, wet days and snow on the ground from Turlock #2, CA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 55° | 39° | 3.0" | 0.0" | 10 | 0 | 44° – 52° |
| February | 58° | 41° | 3.1" | 0.0" | 10 | 0 | 45° – 54° |
| March | 62° | 43° | 2.4" | 0.0" | 9 | 0 | 47° – 59° |
| April | 67° | 46° | 0.8" | 0.0" | 5 | 0 | 52° – 60° |
| May | 75° | 51° | 0.4" | 0.0" | 3 | 0 | 56° – 68° |
| June | 83° | 57° | 0.1" | 0.0" | 1 | 0 | 66° – 74° |
| July | 90° | 62° | 0.0" | 0.0" | 0 | 0 | 73° – 80° |
| August | 89° | 62° | 0.0" | 0.0" | 0 | 0 | 72° – 79° |
| September | 85° | 60° | 0.1" | 0.0" | 1 | 0 | 68° – 76° |
| October | 76° | 53° | 0.6" | 0.0" | 3 | 0 | 61° – 69° |
| November | 63° | 45° | 1.4" | 0.0" | 6 | 0 | 47° – 59° |
| December | 55° | 39° | 2.6" | 0.0" | 10 | 0 | 43° – 50° |
| Year | 72° | 50° | 14.5" | 0.0" | 57 | 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 68°. August is the most reliable, staying within 7°.
Where Diablo Grande’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 Diablo Grande’s center.
- Snow: Turlock #2, CA.
- Frost dates, heating and cooling: Modesto City Co Airport, 23 miles away.
- 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 Diablo Grande’s climate
What is the weather like in Diablo Grande?
A typical July afternoon reaches 90°, a January night drops to 39°, and snow is almost unheard of. Milder January nights than 88% of U.S. towns; hotter July afternoons than 75% of U.S. towns.
How cold does it get in Diablo Grande in winter?
December nights average 39°. About 12 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 43°.
How much snow does Diablo Grande get?
About 0.0 inches in a normal winter at Turlock #2, CA, so most winters see none.
How hot does it get in Diablo Grande?
July, with a typical high of 90° and a low of 62°. About 90 days a year reach 90° (Modesto City Co Airport).
When is the first and last frost in Diablo Grande?
In half of years the last spring frost (32°) comes by January 31 and the first fall frost by December 5, about 312 frost-free days, at Modesto City Co Airport.
What growing zone is Diablo Grande in?
Zone 9b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 29°.
What is the best time of year to visit Diablo Grande?
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 Diablo Grande getting warmer?
Yes: 1991–2020 averaged 1.6° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 68% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Diablo Grande.
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.