Sunnyvale reaches 100° on about 22 days a year, more than 96% of U.S. towns
A typical July afternoon reaches 95°, a January night drops to 36°, and snow is almost unheard of.
A year in Sunnyvale at a glance
Each month’s typical high and low, and what it brings.
What stands out about Sunnyvale’s climate
Compared with towns across the U.S., with Sunnyvale’s place in Texas beside it.
What a year in Sunnyvale feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 272 frost-free days a year
In half of years the last 32° night comes by March 2 and the first by November 29. Frost and day counts come from NOAA’s station at Dallas Love Fld, TX, 18 miles from the town’s center, at about the same height.
The 2023 USDA map puts Sunnyvale’s center in zone 8b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 18°. 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 40 inches of rain a year
May is the wettest month and July the driest. Rain falls on about 85 days a year. Snow is rare: about 0.2" in a normal year at Rockwall, TX, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Sunnyvale
39% of the work is heating, so air conditioning is the bigger bill. Months averaging under 55° run from December through February.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Dallas Love Fld, TX.
Living with Sunnyvale’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
272 frost-free days in zone 8b. The last frost comes by Mar 2 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Nov 29.
Months with highs of 62–84° and lows of 40° or more: March, April, May, October and November. 7.1 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Sunnyvale from natural hazards, river flooding is the largest share (40%); heat waves, cold waves, winter storms and ice storms together are 30%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Sunnyvale and its neighbors
Every town next door is within a degree of Sunnyvale in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Sunnyvale’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 |
|---|---|---|---|---|
| Sunnyvale, TX | 36° | 95° | 40" | 0.2" |
| Clearlake, CA | 35° | 93° | 40" | 0.4" |
| Cayce, SC | 35° | 93° | 46" | 1.2" |
| Milledgeville, GA | 34° | 93° | 47" | 0.6" |
| Tecumseh, OK | 28° | 93° | 40" | 1.4" |
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 Sunnyvale averaged 0.8° warmer than the 1900s. The biggest change is in January (+1.9°).
A smaller shift than in 89% 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 Sunnyvale compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Sunnyvale’s place among Texas’.
Sunnyvale weather by month
Highs, lows and precipitation from NOAA’s grid at Sunnyvale’s center; snow, wet days and snow on the ground from Rockwall, TX. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 56° | 36° | 2.8" | 0.1" | 8 | 0 | 41° – 54° |
| February | 61° | 40° | 2.9" | 0.1" | 8 | 0 | 41° – 59° |
| March | 68° | 47° | 3.7" | 0.0" | 9 | 0 | 52° – 64° |
| April | 76° | 54° | 3.3" | 0.0" | 7 | 0 | 60° – 71° |
| May | 83° | 63° | 4.7" | 0.0" | 9 | 0 | 69° – 78° |
| June | 91° | 71° | 3.9" | 0.0" | 8 | 0 | 78° – 85° |
| July | 95° | 74° | 2.0" | 0.0" | 5 | 0 | 80° – 90° |
| August | 96° | 74° | 2.3" | 0.0" | 5 | 0 | 79° – 92° |
| September | 89° | 67° | 3.0" | 0.0" | 5 | 0 | 74° – 85° |
| October | 79° | 55° | 4.7" | 0.0" | 7 | 0 | 62° – 72° |
| November | 67° | 45° | 3.1" | 0.0" | 7 | 0 | 50° – 62° |
| December | 58° | 37° | 3.4" | 0.0" | 8 | 0 | 40° – 52° |
| Year | 76° | 55° | 39.9" | 0.2" | 85 | 0 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 41° to 59°. June is the most reliable, staying within 8°.
Where Sunnyvale’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 Sunnyvale’s center.
- Snow: Rockwall, TX.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Dallas Love Fld, TX, 18 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 Sunnyvale’s climate
What is the weather like in Sunnyvale?
A typical July afternoon reaches 95°, a January night drops to 36°, and snow is almost unheard of. Milder January nights than 82% of U.S. towns; hotter July afternoons than 95% of U.S. towns.
How cold does it get in Sunnyvale in winter?
January nights average 36°. About 23 nights a year reach 32° or below. In the coldest January of the last 30 years the month averaged 41°.
How much snow does Sunnyvale get?
About 0.2 inches in a normal winter at Rockwall, TX, so most winters see none.
How hot does it get in Sunnyvale?
July, with a typical high of 95° and a low of 74°. About 108 days a year reach 90° and 22 reach 100° (Dallas Love Fld, TX).
When is the first and last frost in Sunnyvale?
In half of years the last spring frost (32°) comes by March 2 and the first fall frost by November 29, about 272 frost-free days, at Dallas Love Fld, TX.
What growing zone is Sunnyvale in?
Zone 8b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 18°.
What is the best time of year to visit Sunnyvale?
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 Sunnyvale getting warmer?
Yes: 1991–2020 averaged 0.8° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 89% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Sunnyvale.
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.