Photo: Marine 69-71 · CC BY-SA 4.0Duncan reaches 100° on about 40 days a year, more than 98% of U.S. towns
On a normal January night the air cools to about 27°. Its yearly precipitation falls short of 97% of U.S. towns. The latest 30-year average runs 1.5° warmer than 1901–2000’s, with March up the most. The frost-free window for a garden runs roughly April 24 to October 25.
A year in Duncan at a glance
Each month’s typical high and low, and what it brings.
What stands out about Duncan’s climate
Compared with towns across the U.S., with Duncan’s place in Arizona beside it.
What a year in Duncan feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 183 frost-free days a year
In half of years the last 32° night comes by April 24 and the first by October 25. Frost and day counts come from NOAA’s station at Duncan, AZ, 1.9 miles from the town’s center, at about the same height.
The 2023 USDA map puts Duncan’s center in zone 8a: the coldest night of a typical winter, averaged over 1991–2020, reaches about 11°. 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 1 inches of snow a winter
Snow, measured at Redrock 1 Nne, NM, falls mostly in January and December. Precipitation (rain plus melted snow) adds up to 11 inches a year; August is the wettest month and April the driest. Rain or snow falls on about 63 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Duncan
63% of the work is heating. Months averaging under 55° run from November through March.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Duncan, AZ.
Living with Duncan’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
183 frost-free days in zone 8a. The last frost comes by Apr 24 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 25.
Months with highs of 62–84° and lows of 40° or more: April and October. 1.1 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Duncan from natural hazards, river flooding is the largest share (74%); heat waves, cold waves, winter storms and ice storms together are 10%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Duncan and similar climates
TownRatings has no climate map of the towns around Duncan yet.
Climates most like Duncan’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 |
|---|---|---|---|---|
| Duncan, AZ | 27° | 97° | 11" | 1.0" |
| Kermit, TX | 30° | 98° | 12" | 1.9" |
| Carlsbad, NM | 29° | 97° | 13" | 2.7" |
| Rosamond, CA | 33° | 98° | 8" | 1.2" |
| Ivins, UT | 32° | 100° | 11" | 1.2" |
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 Duncan averaged 1.5° warmer than the 1900s. The biggest change is in March (+2.0°).
A bigger shift than in 58% 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 Duncan compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Duncan’s place among Arizona’s.
Duncan weather by month
Highs, lows and precipitation from NOAA’s grid at Duncan’s center; snow, wet days and snow on the ground from Redrock 1 Nne, NM. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 59° | 27° | 1.0" | 0.5" | 5 | 0 | 40° – 48° |
| February | 64° | 31° | 0.9" | 0.0" | 5 | 0 | 43° – 52° |
| March | 71° | 36° | 0.6" | 0.0" | 3 | 0 | 49° – 58° |
| April | 79° | 42° | 0.2" | 0.0" | 2 | 0 | 55° – 65° |
| May | 88° | 50° | 0.3" | 0.0" | 3 | 0 | 64° – 74° |
| June | 97° | 60° | 0.2" | 0.0" | 4 | 0 | 73° – 82° |
| July | 97° | 67° | 1.9" | 0.0" | 11 | 0 | 79° – 85° |
| August | 95° | 66° | 2.4" | 0.0" | 10 | 0 | 77° – 86° |
| September | 90° | 59° | 1.4" | 0.0" | 7 | 0 | 70° – 78° |
| October | 81° | 46° | 0.8" | 0.0" | 4 | 0 | 60° – 70° |
| November | 68° | 34° | 0.7" | 0.0" | 3 | 0 | 45° – 58° |
| December | 59° | 27° | 1.0" | 0.5" | 5 | 0 | 40° – 46° |
| Year | 79° | 45° | 11.2" | 1.0" | 63 | 0 |
How much a month can swing
A normal is an average. November swings the most: from 1991 to 2020 its average ranged from 45° to 58°. December is the most reliable, staying within 6°.
Where Duncan’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 Duncan’s center.
- Snow: Redrock 1 Nne, NM.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Duncan, AZ, 1.9 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 Duncan’s climate
What is the weather like in Duncan?
A typical July afternoon reaches 97°, a January night drops to 27°, and about 1 inches of snow falls in a normal winter. Milder January nights than 69% of U.S. towns; hotter July afternoons than 98% of U.S. towns.
How cold does it get in Duncan in winter?
December nights average 27°. About 113 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 40°.
How much snow does Duncan get?
About 1.0 inches in a normal winter at Redrock 1 Nne, NM, most of it in January and December, with snow on the ground about 0 days a year.
How hot does it get in Duncan?
July, with a typical high of 97° and a low of 67°. About 130 days a year reach 90° and 40 reach 100° (Duncan, AZ).
When is the first and last frost in Duncan?
In half of years the last spring frost (32°) comes by April 24 and the first fall frost by October 25, about 183 frost-free days, at Duncan, AZ.
What growing zone is Duncan in?
Zone 8a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 11°.
What is the best time of year to visit Duncan?
By one simple rule (highs of 62–84° and lows of 40° or more), April and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Duncan getting warmer?
Yes: 1991–2020 averaged 1.5° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 58% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Duncan.
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.