Rillito reaches 100° on about 73 days a year, more than all but 104 U.S. towns
January mornings start at about 39°. By precipitation alone, it ranks drier than 97% of U.S. towns. March has warmed most since 1901–2000, part of a 1.4° rise. The frost-free window for a garden runs roughly February 26 to December 4.
A year in Rillito at a glance
Each month’s typical high and low, and what it brings.
What stands out about Rillito’s climate
Compared with towns across the U.S., with Rillito’s place in Arizona beside it.
What a year in Rillito feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 279 frost-free days a year
In half of years the last 32° night comes by February 26 and the first by December 4. Frost and day counts come from NOAA’s station at Tohono Chul, AZ, 11 miles from the town’s center, 480 ft higher.
The 2023 USDA map puts Rillito’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 11 inches of rain a year
August is the wettest month and June the driest. Rain falls on about 45 days a year. Snow is rare: about 0.0" in a normal year at Tucson 17 Nw, AZ, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Rillito
33% 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 Tohono Chul, AZ.
Living with Rillito’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
279 frost-free days in zone 9b. The last frost comes by Feb 26 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 4.
Months with highs of 62–84° and lows of 40° or more: February, March and November. 0.0 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Rillito from natural hazards, river flooding is the largest share (51%); heat waves, cold waves, winter storms and ice storms together are 37%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Rillito and similar climates
TownRatings has no climate map of the towns around Rillito yet.
Climates most like Rillito’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 |
|---|---|---|---|---|
| Rillito, AZ | 39° | 102° | 11" | 0.0" |
| Hillcrest, CA | 40° | 100° | 10" | 0.1" |
| Enterprise, NV | 37° | 103° | 5" | 0.2" |
| St. George, UT | 33° | 103° | 8" | 1.2" |
| Eagle Pass, TX | 41° | 98° | 19" | 0.0" |
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 Rillito averaged 1.4° warmer than the 1900s. The biggest change is in March (+2.4°).
A bigger shift than in 55% 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 Rillito compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Rillito’s place among Arizona’s.
Rillito weather by month
Highs, lows and precipitation from NOAA’s grid at Rillito’s center; snow, wet days and snow on the ground from Tucson 17 Nw, AZ. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 67° | 39° | 0.9" | 0.0" | 4 | 0 | 49° – 58° |
| February | 70° | 41° | 1.1" | 0.0" | 4 | 0 | 51° – 61° |
| March | 77° | 46° | 0.7" | 0.0" | 3 | 0 | 55° – 67° |
| April | 84° | 51° | 0.3" | 0.0" | 1 | 0 | 61° – 73° |
| May | 93° | 60° | 0.3" | 0.0" | 1 | 0 | 71° – 81° |
| June | 103° | 69° | 0.2" | 0.0" | 1 | 0 | 81° – 89° |
| July | 102° | 75° | 1.5" | 0.0" | 8 | 0 | 86° – 91° |
| August | 101° | 74° | 2.1" | 0.0" | 8 | 0 | 85° – 92° |
| September | 97° | 69° | 1.1" | 0.0" | 5 | 0 | 78° – 85° |
| October | 88° | 57° | 0.6" | 0.0" | 3 | 0 | 69° – 77° |
| November | 76° | 46° | 0.7" | 0.0" | 2 | 0 | 52° – 67° |
| December | 66° | 38° | 1.1" | 0.0" | 4 | 0 | 48° – 57° |
| Year | 85° | 55° | 10.6" | 0.0" | 45 | 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 5°.
Where Rillito’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 Rillito’s center.
- Snow: Tucson 17 Nw, AZ.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Tohono Chul, AZ, 11 miles from the town’s center, 480 ft higher; 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 Rillito’s climate
What is the weather like in Rillito?
A typical July afternoon reaches 102°, a January night drops to 39°, and snow is almost unheard of. Milder January nights than 87% of U.S. towns; hotter July afternoons than all but 100 U.S. towns.
How cold does it get in Rillito in winter?
December nights average 38°. About 20 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 48°.
How much snow does Rillito get?
About 0.0 inches in a normal winter at Tucson 17 Nw, AZ, so most winters see none.
How hot does it get in Rillito?
July, with a typical high of 102° and a low of 75°. About 159 days a year reach 90° and 73 reach 100° (Tohono Chul, AZ).
When is the first and last frost in Rillito?
In half of years the last spring frost (32°) comes by February 26 and the first fall frost by December 4, about 279 frost-free days, at Tohono Chul, AZ.
What growing zone is Rillito 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 Rillito?
By one simple rule (highs of 62–84° and lows of 40° or more), February, March and November. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Rillito getting warmer?
Yes: 1991–2020 averaged 1.4° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 55% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Rillito.
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.