Robson Ranch, Arizona climate: Climate normals at a NOAA weather station
Robson Ranch's normal year runs from 37°F December nights to 105°F July afternoons, with 7.8 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 21.8°C, December lows of 3°C, July highs of 41°C, 197 mm of precipitation a year.
- NOAA stationRobson Ranch
- Station IDUSC00027187
- Location32.81°N 111.63°W
- Elevation1,495 ft (456 m)
On October 23, the normal high in Robson Ranch is 86°F and the normal low 55°F, and the chance of measurable rain or snow is 6%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Robson Ranch.
- Jan 67° 38°
- Feb 71° 42°
- Mar 80° 47°
- Apr 87° 52°
- May 95° 60°
- Jun 106° 69°
- Jul 105° 76°
- Aug 104° 75°
- Sep 99° 69°
- Oct 89° 57°
- Nov 76° 45°
- Dec 65° 37°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like at Robson Ranch each month?
July is the warmest month, with normal highs of 105°F; December the coldest, with normal lows of 37°F. The most precipitation falls in January (1.11 in), the least in May (0.13 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 67°F | 38°F | 52.4°F | 1.11 | 4 | <1 | 7 | 10 h 10 min |
| February | 71°F | 42°F | 56.5°F | 1.01 | 3 | <1 | 3 | 11 h |
| March | 80°F | 47°F | 63.3°F | 0.71 | 2 | 3 | <1 | 12 h |
| April | 87°F | 52°F | 69.7°F | 0.20 | 1 | 13 | <1 | 13 h |
| May | 95°F | 60°F | 77.5°F | 0.13 | 1 | 24 | <1 | 13 h 50 min |
| June | 106°F | 69°F | 87.7°F | 0.32 | 1 | 30 | <1 | 14 h 20 min |
| July | 105°F | 76°F | 90.9°F | 0.75 | 5 | 31 | <1 | 14 h 10 min |
| August | 104°F | 75°F | 89.4°F | 0.89 | 5 | 31 | <1 | 13 h 20 min |
| September | 99°F | 69°F | 83.6°F | 0.47 | 3 | 28 | <1 | 12 h 30 min |
| October | 89°F | 57°F | 72.9°F | 0.78 | 2 | 16 | <1 | 11 h 30 min |
| November | 76°F | 45°F | 60.4°F | 0.52 | 2 | 1 | 1 | 10 h 30 min |
| December | 65°F | 37°F | 51.4°F | 0.86 | 4 | <1 | 7 | 10 h |
| Year (annual) | 87°F | 56°F | 71.3°F | 7.75 | 33 | 176 | 18 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 19°C | 3°C | 11.3°C | 28 mm |
| February | 22°C | 5°C | 13.6°C | 26 mm |
| March | 27°C | 8°C | 17.4°C | 18 mm |
| April | 31°C | 11°C | 20.9°C | 5 mm |
| May | 35°C | 15°C | 25.3°C | 3 mm |
| June | 41°C | 21°C | 30.9°C | 8 mm |
| July | 41°C | 25°C | 32.7°C | 19 mm |
| August | 40°C | 24°C | 31.9°C | 23 mm |
| September | 37°C | 20°C | 28.7°C | 12 mm |
| October | 31°C | 14°C | 22.7°C | 20 mm |
| November | 24°C | 7°C | 15.8°C | 13 mm |
| December | 19°C | 3°C | 10.8°C | 22 mm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00027187; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
Which months are mildest at Robson Ranch?
Normal highs sit between 65°F and 85°F in January, February, March, November and December. Of those, November has the fewest days with rain (2).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00027187.
When is the last frost at Robson Ranch?
In Robson Ranch, the last spring frost (32°F) comes after February 7 in half of years and after March 4 in one year in ten; the first autumn frost comes before December 3 in half of years and before November 17 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- February 71 year in 10 after March 4; 9 in 10 after January 10
- First autumn frost, half of years before
- December 31 year in 10 before November 17; 9 in 10 before December 21
NOAA puts the median frost-free season at 298 days, and the season without a hard freeze (28°F) at 334 days.
A hard freeze (28°F) comes after January 17 in half of springs and before December 17 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Robson Ranch in zone 9a in ZIP code 85194, the nearest ZIP area.
Frost dates for every NOAA station in Arizona · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00027187; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get at Robson Ranch?
In a normal year in Robson Ranch, 176 days a year reach 90°F (111 of them 100°F or more), 18 nights fall to 32°F or colder and 33 days bring measurable precipitation.
- Days at 90°F or more
- 176a normal year
- Days at 100°F or more
- 111a normal year
- Nights at 32°F or colder
- 18a normal year
- Days that stay below freezing
- fewer than 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 33a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00027187.
How sunny is it at Robson Ranch?
Over a year 92% of the sunlight that would reach the ground under clear skies gets through the clouds at Robson Ranch, 5.9 kWh per square metre a day. June is the sunniest month (96%) and December the cloudiest (86%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 87% | 3.6 |
| February | 87% | 4.6 |
| March | 91% | 6.0 |
| April | 94% | 7.4 |
| May | 95% | 8.2 |
| June | 96% | 8.4 |
| July | 88% | 7.2 |
| August | 90% | 6.7 |
| September | 92% | 6.1 |
| October | 94% | 5.1 |
| November | 91% | 3.9 |
| December | 86% | 3.3 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How many heating and cooling degree days does Robson Ranch record?
A normal year at Robson Ranch brings 1,363 heating degree days, 75% fewer than the median U.S. place (5,373), and 3,693 cooling degree days, 4.1 times the median (908). Two months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 7,917 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 392 | 0 |
| February | 242 | 4 |
| March | 101 | 48 |
| April | 20 | 159 |
| May | 1 | 390 |
| June | 0 | 681 |
| July | 0 | 803 |
| August | 0 | 756 |
| September | 0 | 558 |
| October | 14 | 259 |
| November | 172 | 35 |
| December | 421 | 0 |
| Year (annual) | 1,363 | 3,693 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00027187. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Have recent years at Robson Ranch been warmer than normal?
2025 averaged 73.0°F, 1.7°F above the 1991-2020 normal of 71.3°F. 5 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 72.0°F | +0.7°F | 9.48 |
| 2022 | 71.6°F | +0.3°F | 12.91 |
| 2023 | 71.8°F | +0.5°F | 7.12 |
| 2024 | 72.7°F | +1.4°F | 7.51 |
| 2025 | 73.0°F | +1.7°F | 6.56 |
Source: observed years: ACIS, station USC00027187. A year counts only with all twelve months complete.
How does Robson Ranch's climate compare?
Robson Ranch is warmer than 71 of the 97 places with their own NOAA record in Arizona, and wetter than 20. Across the 7,247 U.S. stations with normals, its annual mean of 71.3°F is warmer than 96%.
In the Köppen classification computed from these normals, Robson Ranch is BWh: hot desert. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Questions about Robson Ranch's climate
What is the coldest month at Robson Ranch?
December, with a normal high of 65°F and a normal low of 37°F. The warmest is July (105°F by day, 76°F at night).
What is the rainiest month at Robson Ranch?
January, with 1.11 in of precipitation in a normal year; the driest is May with 0.13 in.
What plant hardiness zone is Robson Ranch in?
The USDA's 2023 map puts Robson Ranch in zone 9a in ZIP code 85194, the nearest ZIP area.
How late can frost come at Robson Ranch?
In half of years the last 32°F night comes after February 7; in one year in ten it comes after March 4. Waiting until March 4 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Arizona climateThe statewide normals and every place in the state
- Arizona City, AZ7 miles from this station, 68.9°F a year
- Eloy, AZ7 miles from this station, 70.9°F a year
- Casa Grande, AZ7 miles from this station, 72.4°F a year
- Coolidge, AZ14 miles from this station, 71.3°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made