Photo: Ken Lund from Reno, Nevada, USA · CC BY-SA 2.0Riverdale reaches 100° on about 42 days a year, more than 98% of U.S. towns
The depth of winter brings overnight lows near 38°. A year here swings 61° from midwinter lows to midsummer highs. Its yearly precipitation falls short of almost every U.S. town. The frost-free window for a garden runs roughly February 24 to November 22.
A year in Riverdale at a glance
Each month’s typical high and low, and what it brings.
What stands out about Riverdale’s climate
Compared with towns across the U.S., with Riverdale’s place in California beside it.
What a year in Riverdale feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 265 frost-free days a year
In half of years the last 32° night comes by February 24 and the first by November 22. Frost and day counts come from NOAA’s station at Lemoore Reeves Nas, CA, 8 miles from the town’s center, at about the same height.
The 2023 USDA map puts Riverdale’s center in zone 9a: 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 8 inches of rain a year
January is the wettest month and July the driest. Rain falls on about 42 days a year. Snow is rare: about 0.0" in a normal year at Hanford 1 S, CA, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Riverdale
58% of the work is heating. Months averaging under 55° run from November through February.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Lemoore Reeves Nas, CA.
Living with Riverdale’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
265 frost-free days in zone 9a. The last frost comes by Feb 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 Nov 22.
Months with highs of 62–84° and lows of 40° or more: February, March, April, October and November. 0.9 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Riverdale from natural hazards, drought is the largest share (67%); heat waves, cold waves, winter storms and ice storms together are 2%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Riverdale and similar climates
TownRatings has no climate map of the towns around Riverdale yet.
Climates most like Riverdale’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 |
|---|---|---|---|---|
| Riverdale, CA | 38° | 98° | 8" | 0.0" |
| Sahuarita, AZ | 37° | 99° | 12" | 0.1" |
| Canutillo, TX | 32° | 96° | 9" | 0.0" |
| Anthony, NM | 31° | 96° | 9" | 0.0" |
| Summerlin South, NV | 35° | 102° | 5" | 0.2" |
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 Riverdale averaged 1.7° warmer than the 1900s. The biggest change is in September (+2.4°).
A bigger shift than in 74% 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 Riverdale compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Riverdale’s place among California’s.
Riverdale weather by month
Highs, lows and precipitation from NOAA’s grid at Riverdale’s center; snow, wet days and snow on the ground from Hanford 1 S, CA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 56° | 38° | 1.7" | 0.0" | 8 | 0 | 42° – 52° |
| February | 63° | 41° | 1.4" | 0.0" | 8 | 0 | 48° – 56° |
| March | 69° | 45° | 1.5" | 0.0" | 6 | 0 | 51° – 63° |
| April | 76° | 48° | 0.7" | 0.0" | 4 | 0 | 56° – 66° |
| May | 84° | 55° | 0.4" | 0.0" | 2 | 0 | 61° – 76° |
| June | 92° | 60° | 0.1" | 0.0" | 1 | 0 | 72° – 81° |
| July | 98° | 65° | 0.0" | 0.0" | 0 | 0 | 78° – 85° |
| August | 97° | 64° | 0.0" | 0.0" | 0 | 0 | 77° – 85° |
| September | 92° | 60° | 0.1" | 0.0" | 1 | 0 | 71° – 79° |
| October | 81° | 51° | 0.4" | 0.0" | 2 | 0 | 62° – 70° |
| November | 66° | 42° | 0.6" | 0.0" | 4 | 0 | 48° – 60° |
| December | 57° | 37° | 1.3" | 0.0" | 7 | 0 | 43° – 51° |
| Year | 77° | 51° | 8.1" | 0.0" | 42 | 0 |
How much a month can swing
A normal is an average. May swings the most: from 1991 to 2020 its average ranged from 61° to 76°. July is the most reliable, staying within 8°.
Where Riverdale’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 Riverdale’s center.
- Snow: Hanford 1 S, CA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Lemoore Reeves Nas, CA, 8 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 Riverdale’s climate
What is the weather like in Riverdale?
A typical July afternoon reaches 98°, a January night drops to 38°, and snow is almost unheard of. Milder January nights than 86% of U.S. towns; hotter July afternoons than 98% of U.S. towns.
How cold does it get in Riverdale in winter?
December nights average 37°. About 29 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 43°.
How much snow does Riverdale get?
About 0.0 inches in a normal winter at Hanford 1 S, CA, so most winters see none.
How hot does it get in Riverdale?
July, with a typical high of 98° and a low of 65°. About 120 days a year reach 90° and 42 reach 100° (Lemoore Reeves Nas, CA).
When is the first and last frost in Riverdale?
In half of years the last spring frost (32°) comes by February 24 and the first fall frost by November 22, about 265 frost-free days, at Lemoore Reeves Nas, CA.
What growing zone is Riverdale in?
Zone 9a 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 Riverdale?
By one simple rule (highs of 62–84° and lows of 40° or more), February, March, April, October and November. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Riverdale getting warmer?
Yes: 1991–2020 averaged 1.7° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 74% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Riverdale.
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.