Photo: $1LENCE D00600D · CC BY-SA 3.0Summit reaches 100° on about 68 days a year, more than all but 109 U.S. towns
On a normal January night the air cools to about 38°. Temperatures cover 63° across the year, low to high. By precipitation alone, it ranks drier than 96% of U.S. towns. Garden chairs stay out from February to April and November, the months with highs of 70–83°.
A year in Summit at a glance
Each month’s typical high and low, and what it brings.
What stands out about Summit’s climate
Compared with towns across the U.S., with Summit’s place in Arizona beside it.
What a year in Summit feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 307 frost-free days a year
In half of years the last 32° night comes by February 5 and the first by December 9. Frost and day counts come from NOAA’s station at Tucson International Airport, 5 miles from the town’s center, at about the same height.
The 2023 USDA map puts Summit’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 12 inches of rain a year
July is the wettest month and May the driest. Rain falls on about 47 days a year. Snow is rare: about 0.1" in a normal year at Tucson International Airport, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Summit
28% 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 Tucson International Airport.
Living with Summit’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
307 frost-free days in zone 9b. The last frost comes by Feb 5 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 9.
Months with highs of 62–84° and lows of 40° or more: February, March, April and November. 0.2 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Summit from natural hazards, river flooding is the largest share (48%); heat waves, cold waves, winter storms and ice storms together are 35%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Summit and its neighbors
Every town next door is within a degree of Summit in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Summit’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 |
|---|---|---|---|---|
| Summit, AZ | 38° | 100° | 12" | 0.1" |
| Hillcrest, CA | 40° | 100° | 10" | 0.1" |
| Ivins, UT | 32° | 100° | 11" | 1.2" |
| Summerlin South, NV | 35° | 102° | 5" | 0.2" |
| Eagle Pass, TX | 41° | 98° | 19" | 0.0" |
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 Summit averaged 1.4° warmer than the 1900s. The biggest change is in March (+2.3°).
A bigger shift than in 52% 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 Summit compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Summit’s place among Arizona’s.
Summit weather by month
Highs, lows and precipitation from NOAA’s grid at Summit’s center; snow, wet days and snow on the ground from Tucson International Airport. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 67° | 38° | 0.8" | 0.0" | 4 | 0 | 48° – 58° |
| February | 70° | 40° | 0.9" | 0.1" | 4 | 0 | 50° – 61° |
| March | 76° | 45° | 0.6" | 0.0" | 3 | 0 | 54° – 66° |
| April | 83° | 50° | 0.3" | 0.0" | 2 | 0 | 61° – 71° |
| May | 92° | 58° | 0.2" | 0.0" | 1 | 0 | 69° – 79° |
| June | 101° | 68° | 0.2" | 0.0" | 2 | 0 | 79° – 88° |
| July | 100° | 74° | 2.4" | 0.0" | 9 | 0 | 84° – 90° |
| August | 98° | 73° | 2.3" | 0.0" | 9 | 0 | 83° – 91° |
| September | 95° | 67° | 1.4" | 0.0" | 4 | 0 | 77° – 83° |
| October | 87° | 55° | 0.7" | 0.0" | 3 | 0 | 67° – 75° |
| November | 76° | 44° | 0.6" | 0.0" | 3 | 0 | 52° – 67° |
| December | 66° | 38° | 1.1" | 0.0" | 4 | 0 | 48° – 56° |
| Year | 84° | 54° | 11.5" | 0.1" | 47 | 0 |
How much a month can swing
A normal is an average. November swings the most: from 1991 to 2020 its average ranged from 52° to 67°. July is the most reliable, staying within 6°.
Where Summit’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 Summit’s center.
- Snow: Tucson International Airport.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Tucson International Airport, 5 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 Summit’s climate
What is the weather like in Summit?
A typical July afternoon reaches 100°, 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 all but 128 U.S. towns.
How cold does it get in Summit in winter?
December nights average 38°. About 12 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 48°.
How much snow does Summit get?
About 0.1 inches in a normal winter at Tucson International Airport, so most winters see none.
How hot does it get in Summit?
July, with a typical high of 100° and a low of 74°. About 158 days a year reach 90° and 68 reach 100° (Tucson International Airport).
When is the first and last frost in Summit?
In half of years the last spring frost (32°) comes by February 5 and the first fall frost by December 9, about 307 frost-free days, at Tucson International Airport.
What growing zone is Summit 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 Summit?
By one simple rule (highs of 62–84° and lows of 40° or more), February, March, April and November. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Summit getting warmer?
Yes: 1991–2020 averaged 1.4° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 52% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Summit.
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.