Rio Rico, Arizona climate: Normal weather by month, frost dates and records
Rio Rico's normal year runs from 28°F December nights to 94°F July afternoons, with 16.1 inches of precipitation and less than an inch of snow (0.3 in) a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 16.9°C, December lows of −2°C, July highs of 35°C, 409 mm of precipitation a year.
- NOAA stationNogales (6 mi N)
- Station IDUSC00025924
- Location31.46°N 110.97°W
- Elevation3,461 ft (1,055 m)
- From the center3 miles
- Population (census place)21,798
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Rio Rico.
- Jan 65° 28°
- Feb 67° 31°
- Mar 73° 35°
- Apr 79° 40°
- May 87° 46°
- Jun 97° 56°
- Jul 94° 65°
- Aug 92° 64°
- Sep 91° 58°
- Oct 84° 45°
- Nov 73° 34°
- Dec 65° 28°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Rio Rico each month?
July is the warmest month, with normal highs of 94°F; December the coldest, with normal lows of 28°F. The most precipitation falls in August (3.91 in), the least in May (0.17 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 65°F | 28°F | 46.8°F | 0.98 | 5 | <1 | 24 | 10 h 20 min |
| February | 67°F | 31°F | 48.8°F | 0.92 | 5 | <1 | 17 | 11 h |
| March | 73°F | 35°F | 53.9°F | 0.69 | 4 | <1 | 10 | 12 h |
| April | 79°F | 40°F | 59.4°F | 0.35 | 2 | 3 | 4 | 12 h 50 min |
| May | 87°F | 46°F | 66.9°F | 0.17 | 1 | 13 | <1 | 13 h 40 min |
| June | 97°F | 56°F | 76.4°F | 0.68 | 2 | 27 | <1 | 14 h 10 min |
| July | 94°F | 65°F | 79.8°F | 3.59 | 14 | 25 | <1 | 14 h |
| August | 92°F | 64°F | 78.2°F | 3.91 | 14 | 23 | <1 | 13 h 20 min |
| September | 91°F | 58°F | 74.0°F | 2.23 | 7 | 20 | <1 | 12 h 20 min |
| October | 84°F | 45°F | 64.1°F | 0.85 | 3 | 8 | 1 | 11 h 30 min |
| November | 73°F | 34°F | 53.9°F | 0.59 | 3 | <1 | 12 | 10 h 30 min |
| December | 65°F | 28°F | 46.3°F | 1.14 | 6 | <1 | 23 | 10 h 10 min |
| Year (annual) | 81°F | 44°F | 62.4°F | 16.10 | 65 | 118 | 92 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 19°C | −2°C | 8.2°C | 25 mm |
| February | 20°C | −1°C | 9.3°C | 23 mm |
| March | 23°C | 2°C | 12.2°C | 18 mm |
| April | 26°C | 4°C | 15.2°C | 9 mm |
| May | 31°C | 8°C | 19.4°C | 4 mm |
| June | 36°C | 13°C | 24.7°C | 17 mm |
| July | 35°C | 19°C | 26.6°C | 91 mm |
| August | 34°C | 18°C | 25.7°C | 99 mm |
| September | 33°C | 14°C | 23.3°C | 57 mm |
| October | 29°C | 7°C | 17.8°C | 22 mm |
| November | 23°C | 1°C | 12.2°C | 15 mm |
| December | 18°C | −2°C | 7.9°C | 29 mm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00025924; 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.
When is the best weather to visit Rio Rico?
Normal highs sit between 65°F and 85°F in January, February, March, April, October and November. Of those, April 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 USC00025924.
When is the last frost in Rio Rico?
In Rio Rico, the last spring frost (32°F) comes after April 16 in half of years and after May 4 in one year in ten; the first autumn frost comes before November 2 in half of years and before October 19 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
- April 161 year in 10 after May 4; 9 in 10 after March 28
- First autumn frost, half of years before
- November 21 year in 10 before October 19; 9 in 10 before November 16
NOAA puts the median frost-free season at 199 days, and the season without a hard freeze (28°F) at 233 days.
A hard freeze (28°F) comes after March 22 in half of springs and before November 14 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Rio Rico in zone 8b across its 2 ZIP code areas (8b in 85648, the largest).
Frost dates for every NOAA station in Arizona · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00025924; 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.
What hardiness zone is each Rio Rico ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Rio Rico's 2 ZIP code areas are all in zone 8b. Each ZIP's frost dates are in the frost tool.
Source: USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; ZIP areas in the place: Census Bureau 2020 ZCTA-to-place relationship file. A ZIP area counts when at least a tenth of its land (and 0.5 km²) lies in the place.
How hot and how cold does it get in Rio Rico?
In a normal year in Rio Rico, 118 days a year reach 90°F (22 of them 100°F or more), 92 nights fall to 32°F or colder and 65 days bring measurable precipitation.
- Days at 90°F or more
- 118a normal year
- Days at 100°F or more
- 22a normal year
- Nights at 32°F or colder
- 92a normal year
- Days that stay below freezing
- fewer than 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 65a normal year
The highest temperature in this station's record (since 1952) is 112°F, on June 26, 1990; the lowest is −4°F, on December 8, 1978.
The wettest calendar year on that record is 1978, with 24.90 in; the snowiest season is 1987–88, with 7.4 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00025924; records: ACIS (NOAA Regional Climate Centers), station USC00025924. Records use complete months only; a month missing more than three days is left out.
How sunny is Rio Rico?
Over a year 89% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Rio Rico, 5.8 kWh per square metre a day. May is the sunniest month (94%) and July the cloudiest (79%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 87% | 3.8 |
| February | 87% | 4.7 |
| March | 90% | 6.2 |
| April | 94% | 7.6 |
| May | 94% | 8.3 |
| June | 92% | 8.1 |
| July | 79% | 6.5 |
| August | 83% | 6.3 |
| September | 87% | 5.8 |
| October | 92% | 5.2 |
| November | 90% | 4.1 |
| December | 87% | 3.5 |
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 much heating and cooling does Rio Rico need?
A normal year in Rio Rico brings 2,596 heating degree days, 52% fewer than the median U.S. place (5,373), and 1,665 cooling degree days, 83% more than the median (908). Five months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 4,976 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 564 | 0 |
| February | 452 | 0 |
| March | 345 | 1 |
| April | 180 | 14 |
| May | 49 | 107 |
| June | 1 | 343 |
| July | 0 | 460 |
| August | 0 | 408 |
| September | 2 | 272 |
| October | 87 | 58 |
| November | 335 | 2 |
| December | 580 | 0 |
| Year (annual) | 2,596 | 1,665 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00025924. 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.
Has Rio Rico been warmer than normal lately?
2025 averaged 64.5°F, 2.1°F above the 1991-2020 normal of 62.4°F. 3 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 62.6°F | +0.2°F | 18.68 |
| 2022 | 61.5°F | −0.9°F | 18.43 |
| 2024 | 63.4°F | +1.0°F | 15.03 |
| 2025 | 64.5°F | +2.1°F | 13.00 |
Source: observed years: ACIS, station USC00025924. A year counts only with all twelve months complete.
How does Rio Rico's climate compare?
Rio Rico is warmer than 39 of the other 96 places with their own NOAA record in Arizona, and wetter than 70. Across the 7,247 U.S. stations with normals, its annual mean of 62.4°F is warmer than 81%.
In the Köppen classification computed from these normals, Rio Rico is BSk: cold semi-arid steppe. 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 Rio Rico's climate
What is the coldest month in Rio Rico?
December, with a normal high of 65°F and a normal low of 28°F. The warmest is July (94°F by day, 65°F at night).
Does it snow in Rio Rico?
Rarely: NOAA's normal is 0.3 inch a year.
What is the rainiest month in Rio Rico?
August, with 3.91 in of precipitation in a normal year; the driest is May with 0.17 in.
What plant hardiness zone is Rio Rico in?
The USDA's 2023 map puts Rio Rico in zone 8b across its 2 ZIP code areas (8b in 85648, the largest).
How late can frost come in Rio Rico?
In half of years the last 32°F night comes after April 16; in one year in ten it comes after May 4. Waiting until May 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
- Nogales, AZ7 miles from this station, 64.8°F a year
- Tumacacori National Monument, AZ9 miles from this station, 63.0°F a year
- Santa Rita Experiment Range, AZ22 miles from this station, 65.3°F a year
- Sonoita, AZ24 miles from this station, 61.6°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made