Photo: The original uploader was Tillman at English Wikipedia. · CC BY 2.0Ajo reaches 100° on about 93 days a year, more than all but 78 U.S. towns
A typical July afternoon reaches 104°, a January night drops to 43°, and snow is almost unheard of.
A year in Ajo at a glance
Each month’s typical high and low, and what it brings.
What stands out about Ajo’s climate
Compared with towns across the U.S., with Ajo’s place in Arizona beside it.
What a year in Ajo feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 93 days a year reach 100°
And 168 days reach 90°. Frost and day counts come from NOAA’s station at Ajo, AZ, 2.1 miles from the town’s center, at about the same height.
The 2023 USDA map puts Ajo’s center in zone 10a: the coldest night of a typical winter, averaged over 1991–2020, reaches about 32°. 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 7 inches of rain a year
August is the wettest month and June the driest. Rain falls on about 23 days a year. Snow is rare: about 0.1" in a normal year at Ajo, AZ, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Ajo
20% of the work is heating, so air conditioning is the bigger bill. Months averaging under 55° run from December.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Ajo, AZ.
Living with Ajo’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
Zone 10a. Frost comes about 8 winters in 10, so the growing year is set by heat, not cold: 93 days at 100° make midsummer the hard season for gardens.
Months with highs of 62–84° and lows of 40° or more: January, February, March, April, November and December. 57 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Ajo from natural hazards, river flooding is the largest share (56%); heat waves, cold waves, winter storms and ice storms together are 31%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Ajo and similar climates
TownRatings has no climate map of the towns around Ajo yet.
Climates most like Ajo’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 |
|---|---|---|---|---|
| Ajo, AZ | 43° | 104° | 7" | 0.1" |
| Desert Hot Springs, CA | 42° | 105° | 7" | 0.8" |
| Henderson, NV | 40° | 105° | 5" | 0.2" |
| St. George, UT | 33° | 103° | 8" | 1.2" |
| Laredo, TX | 45° | 99° | 20" | 0.1" |
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 Ajo averaged 2.5° warmer than the 1900s. The biggest change is in March (+3.5°).
A bigger shift than in all but 81 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 Ajo compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Ajo’s place among Arizona’s.
Ajo weather by month
Highs, lows and precipitation from NOAA’s grid at Ajo’s center; snow, wet days and snow on the ground from Ajo, AZ. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 67° | 43° | 0.7" | 0.1" | 2 | 0 | 51° – 61° |
| February | 71° | 45° | 0.7" | 0.0" | 3 | 0 | 51° – 63° |
| March | 77° | 50° | 0.7" | 0.0" | 2 | 0 | 57° – 71° |
| April | 84° | 55° | 0.2" | 0.0" | 1 | 0 | 63° – 75° |
| May | 92° | 62° | 0.1" | 0.0" | 1 | 0 | 71° – 83° |
| June | 101° | 71° | 0.0" | 0.0" | 0 | 0 | 81° – 91° |
| July | 104° | 78° | 0.9" | 0.0" | 3 | 0 | 87° – 94° |
| August | 103° | 77° | 1.7" | 0.0" | 5 | 0 | 86° – 95° |
| September | 98° | 72° | 0.7" | 0.0" | 2 | 0 | 82° – 90° |
| October | 88° | 61° | 0.4" | 0.0" | 1 | 0 | 70° – 80° |
| November | 76° | 50° | 0.4" | 0.0" | 1 | 0 | 54° – 69° |
| December | 66° | 43° | 0.7" | 0.0" | 3 | 0 | 51° – 59° |
| Year | 86° | 59° | 7.2" | 0.1" | 23 | 0 |
How much a month can swing
A normal is an average. November swings the most: from 1991 to 2020 its average ranged from 54° to 69°. July is the most reliable, staying within 8°.
Where Ajo’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 Ajo’s center.
- Snow: Ajo, AZ.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Ajo, AZ, 2.1 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 Ajo’s climate
What is the weather like in Ajo?
A typical July afternoon reaches 104°, a January night drops to 43°, and snow is almost unheard of. Milder January nights than 92% of U.S. towns; hotter July afternoons than all but 84 U.S. towns.
How cold does it get in Ajo in winter?
December nights average 43°. About 2 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 51°.
How much snow does Ajo get?
About 0.1 inches in a normal winter at Ajo, AZ, so most winters see none.
How hot does it get in Ajo?
July, with a typical high of 104° and a low of 78°. About 168 days a year reach 90° and 93 reach 100° (Ajo, AZ).
When is the first and last frost in Ajo?
There is no reliable frost date: a 32° night comes in about 81% of winters at Ajo, AZ, so most years bring a freeze but some pass without one.
What growing zone is Ajo in?
Zone 10a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 32°.
What is the best time of year to visit Ajo?
By one simple rule (highs of 62–84° and lows of 40° or more), January, February, March, April, November and December. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Ajo getting warmer?
Yes: 1991–2020 averaged 2.5° warmer than 1901–2000 on NOAA’s grid. A bigger shift than all but 81 U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Ajo.
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.