San Tan Valley reaches 100° on about 95 days a year, more than all but 71 U.S. towns
On a normal January night the air cools to about 40°. The year swings widely: the coldest month’s nights and the warmest month’s afternoons are 66° apart. By precipitation alone, it ranks drier than 98% of U.S. towns. Picnics, hikes and garden evenings come into their own from January to March and November, with highs of 67–77°.
A year in San Tan Valley at a glance
Each month’s typical high and low, and what it brings.
What stands out about San Tan Valley’s climate
Compared with towns across the U.S., with San Tan Valley’s place in Arizona beside it.
What a year in San Tan Valley feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 315 frost-free days a year
In half of years the last 32° night comes by February 1 and the first by December 11. Frost and day counts come from NOAA’s station at Chandler Heights, AZ, 7 miles from the city’s center point, 110 ft lower.
The 2023 USDA map puts San Tan Valley’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 9 inches of rain a year
August is the wettest month and June the driest. Rain falls on about 24 days a year. Snow is rare: about 0.0" in a normal year at Florence, AZ, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in San Tan Valley
27% of the work is heating, so air conditioning is the bigger bill. Months averaging under 55°: December and January.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Chandler Heights, AZ.
Living with San Tan Valley’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
315 frost-free days in zone 9b. The last frost comes by Feb 1 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 11.
Months with highs of 62–84° and lows of 40° or more: January, February, March and November. 73 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in San Tan Valley from natural hazards, river flooding is the largest share (65%); heat waves, cold waves, winter storms and ice storms together are 24%. Normals are averages; the hazards page covers the extremes.
Natural hazards →San Tan Valley and its neighbors
Every town next door is within a degree of San Tan Valley in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like San Tan Valley’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 |
|---|---|---|---|---|
| San Tan Valley, AZ | 40° | 105° | 9" | 0.0" |
| Henderson, NV | 40° | 105° | 5" | 0.2" |
| Desert Hot Springs, CA | 42° | 105° | 7" | 0.8" |
| St. George, UT | 33° | 103° | 8" | 1.2" |
| Laredo, TX | 45° | 99° | 20" | 0.1" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in San Tan Valley averaged 2.0° warmer than the 1900s. The biggest change is in March (+2.8°).
A bigger shift than in 90% 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. In a city of 109,000 people, part of the change is the city itself: pavement and buildings hold heat (the urban heat island).
How San Tan Valley compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with San Tan Valley’s place among Arizona’s.
San Tan Valley weather by month
Highs, lows and precipitation from NOAA’s grid at San Tan Valley’s center; snow, wet days and snow on the ground from Florence, AZ. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 67° | 40° | 1.1" | 0.0" | 3 | 0 | 50° – 59° |
| February | 70° | 43° | 1.2" | 0.0" | 4 | 0 | 51° – 62° |
| March | 77° | 47° | 1.0" | 0.0" | 3 | 0 | 55° – 69° |
| April | 85° | 53° | 0.3" | 0.0" | 1 | 0 | 63° – 74° |
| May | 94° | 61° | 0.2" | 0.0" | 1 | 0 | 72° – 83° |
| June | 103° | 70° | 0.1" | 0.0" | 0 | 0 | 81° – 90° |
| July | 105° | 78° | 1.0" | 0.0" | 2 | 0 | 88° – 94° |
| August | 103° | 77° | 1.2" | 0.0" | 3 | 0 | 87° – 94° |
| September | 99° | 71° | 0.8" | 0.0" | 1 | 0 | 81° – 87° |
| October | 88° | 59° | 0.6" | 0.0" | 1 | 0 | 70° – 78° |
| November | 76° | 47° | 0.6" | 0.0" | 1 | 0 | 53° – 67° |
| December | 66° | 39° | 1.0" | 0.0" | 2 | 0 | 50° – 56° |
| Year | 86° | 57° | 9.1" | 0.0" | 24 | 0 |
How much a month can swing
A normal is an average. November swings the most: from 1991 to 2020 its average ranged from 53° to 67°. July is the most reliable, staying within 6°.
Where San Tan Valley’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 San Tan Valley’s center.
- Snow: Florence, AZ.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Chandler Heights, AZ, 7 miles from the city’s center point, 110 ft lower; 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 San Tan Valley’s climate
What is the weather like in San Tan Valley?
A typical July afternoon reaches 105°, a January night drops to 40°, and snow is almost unheard of. Milder January nights than 89% of U.S. towns; hotter July afternoons than all but 70 U.S. towns.
How cold does it get in San Tan Valley in winter?
December nights average 39°. About 11 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 50°.
How much snow does San Tan Valley get?
About 0.0 inches in a normal winter at Florence, AZ, so most winters see none.
How hot does it get in San Tan Valley?
July, with a typical high of 105° and a low of 78°. About 165 days a year reach 90° and 95 reach 100° (Chandler Heights, AZ).
When is the first and last frost in San Tan Valley?
In half of years the last spring frost (32°) comes by February 1 and the first fall frost by December 11, about 315 frost-free days, at Chandler Heights, AZ.
What growing zone is San Tan Valley 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 San Tan Valley?
By one simple rule (highs of 62–84° and lows of 40° or more), January, February, March and November. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is San Tan Valley getting warmer?
Yes: 1991–2020 averaged 2.0° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 90% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in San Tan Valley.
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.