Duncan, AZ Climate: Temperature & Rain by Month
Explore NOAA NCEI's 1991–2020 climate normals → and a clearly labeled PlainClimate comfort calculation
30-year climate normals (1991-2020) from Duncan's primary NOAA station, DUNCAN.
The climate verdict for Duncan
Dryness leads the climate profile for Duncan, Arizona, with 10.4 inches of precipitation a year. NOAA records an annual average of 61°F. It scores 80/100 for climate comfort (excellent), putting it in the top third of station-mapped location scores and exceeding 76% of them.
- 61°F
- average temperature, NOAA 1991-2020 normal
- 80/100
- comfort score, above 76% of station-mapped location scores
- 10.4"
- precipitation, annual total
- 184 days
- frost-free days per growing season
Duncan: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00022754 · Duncan, AZ 61°F mean · 10.4" precip
TEMP-MILD · RANK-UPPER · PHOTO-FINISH · PRCP-ARID · SWING-MID · COMF-TOP · LOAD-MIX · STN-1 · BOOK-FULL
- TEMP-MILD 61°F
- RANK-UPPER #5,352
- PHOTO-FINISH ≈ Aberdeen
- PRCP-ARID 10.4"
- SWING-MID 40°F
- COMF-TOP 80/100
- LOAD-MIX H/C balanced
- STN-1 USC00022754
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Aberdeen, MS (+ 0 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every AZ station list.
- Duncan (this station) 61°F
- Hot Charlotte, NC 61°F
- Near Aberdeen, MS 61°F
- Near Atoka, OK 61°F
- Near Blanchard, OK 61°F
Climate Living Index · Duncan
Duncan: 37/100 · grade F
Duncan publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for Duncan, not an official NOAA rating. Rankings still use Comfort Score 80/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Annual temperature balance | 61.4°F · 6.1° from 67.5°F | 81/100 · B |
| Frost-free season | 184 days/year | 53/100 · D |
| Precipitation balance | 10.4 in · 24.6 from 35 in | 13/100 · F |
| Normal heat + freeze calendar | 239 calendar days | 0/100 · F |
Duncan · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Duncan's normals sit in a dry climate class: BSk
Precipitation is low relative to temperature but above true desert thresholds: cold semi-arid steppe (BSk). Class BSk is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: dry (arid or semi-arid), specifically cold semi-arid steppe.
- Köppen code
- BSk
- Group
- Dry (arid or semi-arid)
- Warmest month
- 81.5°F
- Coldest month
- 42.0°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · balanced station
Where Duncan sits across the climate record
Three NOAA fields for Duncan's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- Top 22% warmest
- Among 6,861 stations, Duncan sits in the warmer third of annual means.
- Annual precipitation
- Drier than 93%
- Duncan's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- 34th percentile swing
- Typical seasonal amplitude versus 6,861 complete station-years.
How Duncan compares across U.S. station-mapped locations
Duncan's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
80 Top 24% score exceeds 76% of 6,189 station-mapped location scores
- 0–10: 0 station-mapped locations (0%). Below this entry.
- 10–20: 0 station-mapped locations (0%). Below this entry.
- 20–30: 96 station-mapped locations (2%). Below this entry.
- 30–40: 280 station-mapped locations (5%). Below this entry.
- 40–50: 1,113 station-mapped locations (18%). Below this entry.
- 50–60: 1,329 station-mapped locations (21%). Below this entry.
- 60–70: 1,236 station-mapped locations (20%). Below this entry.
- 70–80: 650 station-mapped locations (11%). Below this entry.
- 80–90: 921 station-mapped locations (15%). This entry sits in this band.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Duncan's measured station temperature trend
MethodologyAcross 52 complete annual observations from 1950 to 2024, DUNCAN warmed at a fitted rate of 0.17°C per decade. The line shows the fitted change relative to its first year, not raw year-to-year temperatures or a forecast.
- Duncan primary station fitted change +0.17 °C/decade
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|
| January | 60°F (16°C) | 25°F (-4°C) | 43°F (6°C) | 0.9" | 24.6 | 0.0 |
| February | 65°F (18°C) | 29°F (-2°C) | 47°F (8°C) | 0.8" | 19.5 | 0.0 |
| March | 73°F (23°C) | 33°F (1°C) | 53°F (12°C) | 0.5" | 15.1 | 0.1 |
| April | 81°F (27°C) | 39°F (4°C) | 60°F (15°C) | 0.2" | 6.7 | 3.0 |
| May | 89°F (32°C) | 47°F (8°C) | 68°F (20°C) | 0.3" | 0.5 | 16.7 |
| June | 98°F (37°C) | 57°F (14°C) | 78°F (25°C) | 0.3" | 0.0 | 28.3 |
| July | 98°F (36°C) | 66°F (19°C) | 82°F (28°C) | 1.7" | 0.0 | 29.0 |
| August | 96°F (35°C) | 65°F (18°C) | 80°F (27°C) | 2.2" | 0.0 | 27.6 |
| September | 91°F (33°C) | 56°F (14°C) | 74°F (23°C) | 1.2" | 0.0 | 20.0 |
| October | 81°F (27°C) | 43°F (6°C) | 62°F (17°C) | 0.7" | 3.1 | 5.6 |
| November | 69°F (21°C) | 31°F (-1°C) | 50°F (10°C) | 0.6" | 17.8 | 0.0 |
| December | 59°F (15°C) | 25°F (-4°C) | 42°F (6°C) | 1.0" | 25.4 | 0.0 |
The year, day by day
Duncan works both ends of the calendar. Normal highs climb to 99°F by June 21 and hold at or above 90°F on 122 dates, then normal lows drop to freezing or below on 117 dates, bottoming at 24°F around December 22.
When the heat sits
Normal highs reach 90°F from May 20 through September 18, covering 122 dates. The broader mild season, normal highs of 70°F or more, runs March 8 to November 14.
This counts calendar dates whose 1991–2020 normal high reaches 90°F. It is a smaller number than the 90°F+ day counts in the monthly table above, which measure how often the threshold was actually crossed in a typical year. A date can average 88°F and still exceed 90°F in half of all years.
The freezing stretch
The normal low stays at or below 32°F into March 7, then returns to freezing around November 12, covering 117 dates in all.
Derived from the normal daily minimum. This is a different measure from the 50%-probability frost dates shown elsewhere on this page, which come from NOAA’s frost product.
Where the wet dates fall
The likeliest wet date is July 29, when 24% of years recorded at least a hundredth of an inch. The driest is April 30 at 4%. Summed across the calendar, that is about 44 wet dates a year.
The widest day
June 1 carries the biggest normal gap between afternoon and dawn, 43°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Duncan.
Where Duncan Stands Nationally
Summers here run among the most heat-heavy normals calendars in the country: on about 122 days a year the normal daily high itself reaches 90°F — a count fewer than one station in ten exceeds.
Aridity defines the water calendar: about 10 inches in a normal year lands this among the driest tenth of ranked stations.
Duncan earns 2 nationally notable standings (outer quintiles) against 6,860 NOAA 1991–2020 normals stations; only those extremes render.
Monthly Precipitation
Average monthly rainfall
4.0 days with precipitation
4.0 days with precipitation
3.0 days with precipitation
1.4 days with precipitation
1.5 days with precipitation
1.9 days with precipitation
6.8 days with precipitation
7.0 days with precipitation
4.5 days with precipitation
3.1 days with precipitation
2.9 days with precipitation
3.9 days with precipitation
Duncan runs a summer-peaked wet season
39% of Duncan's yearly precipitation falls in June, July and August alone, against the 25% an evenly spread year would give those three months. The wettest month is August at 2.2", on a 39.5°F seasonal spread. Warm-season convection and, across the Southwest, the North American monsoon produce this shape: rain arrives in short heavy bursts during the hottest part of the year rather than as long cool-season soaking.
- Wettest three months: August, July, September, taking 49% of the annual total between them.
- Driest month: April at 0.2".
- Winter share: 27% falls in December, January and February.
Shares are computed from this station's own 1991-2020 monthly precipitation normals. A summer-peaked label means the June-August share reaches 35%; it describes timing across an average year, not any single season, and says nothing about how heavy an individual storm can be.
How Duncan's precipitation splits across the calendar
About 44 days a year record measurable precipitation here, carrying 10.4" between them, or roughly 0.24 inches on a typical wet day. That sits in the middle band: neither the many-light-days pattern of the Pacific Northwest and the Great Lakes, nor the few-heavy-events pattern of the Gulf and the desert Southwest.
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year and say nothing about the heaviest single storm on record.
Frost Dates & Growing Season
First Fall Freeze
October 25
50% probability date
Last Spring Freeze
April 24
50% probability date
Growing Season
184 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
3,091
Higher = more heating needed
Cooling Degree Days
1,801
Higher = more cooling needed
Warmest Month
July
Coldest Month
December
Nationwide similar cities
Other rankable U.S. places outside AZ closest to Duncan on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (61°F here).
- Aberdeen, MS 61°F · 0.0°F off
- Atoka, OK 61°F · 0.0°F off
- Blanchard, OK 61°F · 0.0°F off
- Charlotte, NC 61°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (10.4" here), excluding temperature-peer places.
- Jerome, ID 10.4" · 0.0" off
- Merced, CA 10.4" · 0.0" off
- Rio Rancho, NM 10.4" · 0.0" off
- Lybrook, NM 10.4" · 0.1" off
Scarce-water calendar
Where Duncan's limited precipitation lands
mixed demand · dry · mid swing
Local precipitation is sparse in this otherwise mixed profile. The station reports 10.4 inches annually, within PlainClimate's dry band. Snowfall is not added to the interpretation because its annual value is missing. The monthly distribution matters because the total alone does not reveal the timing.
July and December mark the typical warm and cold ends of the calendar in Duncan's middle-range seasonal profile. The measured spread is 39.5°F. The annual average is 61°F. Neither the annual mean nor one extreme month represents the full calendar on its own.
Heating and cooling both register in Duncan's normal, at 3,091 and 1,801 degree days respectively. Neither total exceeds the other by more than two to one, so the record is better read as a mixed-demand calendar than as heating-led or cooling-led.
A roughly 184-day frost-free season sits inside this mixed heating-and-cooling profile. Start and end dates matter because both sides of the thermostat register during a normal year.
Duncan wettest normal
August
August concentrates the scarce annual total (10.4 inches).
Duncan driest normal
April
April is typically driest; arid stations are defined by when water is absent, not by a four-season grid.
Questions about Duncan's climate
How dry is Duncan? ▼
How many days above 90°F does Duncan get? ▼
How much energy does heating and cooling require in Duncan? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Duncan's primary station: DUNCAN (USC00022754). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The 2024 Census Gazetteer identifies the exact name-and-state match as an incorporated place (GEOID 0420750). Match rule for Duncan: exact normalized name + state only, no fuzzy expansion, so nearby differently spelled facilities stay unmatched.
On this page every temperature, precipitation, and derived score for Duncan comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.