Green Valley is drier than 91% of U.S. towns: 18 inches of precipitation a year
In January the night’s low is typically 13°. Winter nights are cold: in January they are colder than in 89% of U.S. towns. Since 1901–2000, the year has warmed by 1.4°, most of all in January. Picnics, hikes and garden evenings suit May, June and September, with highs of 67–78°.
A year in Green Valley at a glance
Each month’s typical high and low, and what it brings.
What stands out about Green Valley’s climate
Compared with towns across the U.S., with Green Valley’s place in South Dakota beside it.
What a year in Green Valley feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 139 frost-free days a year
In half of years the last 32° night comes by May 12 and the first by October 1. Frost and day counts come from NOAA’s station at Rapid City Rgnl Airport, 2.9 miles from the town’s center, at about the same height.
The 2023 USDA map puts Green Valley’s center in zone 5a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −15°. 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 49 inches of snow a winter
Snow, measured at Rapid City Rgnl Airport, falls mostly in April. Precipitation (rain plus melted snow) adds up to 18 inches a year; May is the wettest month and January the driest. Rain or snow falls on about 96 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Green Valley
92% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Rapid City Rgnl Airport.
Living with Green Valley’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
139 frost-free days in zone 5a. The last frost comes by May 12 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 1.
Months with highs of 62–84° and lows of 40° or more: May, June and September.
Parks & trails →Of the yearly building losses FEMA expects in Green Valley from natural hazards, river flooding is the largest share (31%); heat waves, cold waves, winter storms and ice storms together are 26%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Green Valley and its neighbors
Every town next door is within a degree of Green Valley in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Green Valley’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 |
|---|---|---|---|---|
| Green Valley, SD | 13° | 87° | 18" | 49" |
| Glenwood Springs, CO | 14° | 87° | 15" | 39" |
| Laurel, MT | 15° | 88° | 14" | 48" |
| Doney Park, AZ | 17° | 86° | 16" | 52" |
| Providence, UT | 15° | 89° | 19" | 44" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Green Valley averaged 1.4° warmer than the 1900s. The biggest change is in January (+3.9°).
A bigger shift than in 56% 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 Green Valley compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Green Valley’s place among South Dakota’s.
Green Valley weather by month
Highs, lows and precipitation from NOAA’s grid at Green Valley’s center; snow, wet days and snow on the ground from Rapid City Rgnl Airport. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 37° | 13° | 0.3" | 5.3" | 6 | 11 | 17° – 36° |
| February | 39° | 15° | 0.5" | 7.7" | 7 | 10 | 10° – 37° |
| March | 49° | 24° | 1.0" | 8.4" | 7 | 6 | 23° – 49° |
| April | 58° | 32° | 2.1" | 10.1" | 11 | 4 | 38° – 51° |
| May | 67° | 43° | 3.6" | 1.5" | 13 | 0 | 48° – 61° |
| June | 78° | 53° | 3.1" | 0.0" | 13 | 0 | 60° – 72° |
| July | 87° | 59° | 2.5" | 0.0" | 10 | 0 | 64° – 79° |
| August | 85° | 57° | 1.6" | 0.0" | 8 | 0 | 66° – 76° |
| September | 76° | 47° | 1.3" | 0.1" | 7 | 0 | 56° – 67° |
| October | 61° | 35° | 1.3" | 3.0" | 7 | 1 | 39° – 54° |
| November | 48° | 23° | 0.5" | 5.7" | 5 | 4 | 25° – 45° |
| December | 38° | 15° | 0.4" | 6.7" | 5 | 12 | 17° – 34° |
| Year | 60° | 35° | 18.2" | 48.5" | 96 | 48 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 10° to 37°. August is the most reliable, staying within 10°.
Where Green Valley’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 Green Valley’s center.
- Snow: Rapid City Rgnl Airport.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Rapid City Rgnl Airport, 2.9 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 Green Valley’s climate
What is the weather like in Green Valley?
A typical July afternoon reaches 87°, a January night drops to 13°, and about 49 inches of snow falls in a normal winter. Colder January nights than 89% of U.S. towns; hotter July afternoons than 60% of U.S. towns.
How cold does it get in Green Valley in winter?
January nights average 13°. About 174 nights a year reach 32° or below and 18 reach 0° or below. In the coldest January of the last 30 years the month averaged 17°.
How much snow does Green Valley get?
About 49 inches in a normal winter at Rapid City Rgnl Airport, most of it in April, with snow on the ground about 48 days a year.
How hot does it get in Green Valley?
July, with a typical high of 87° and a low of 59°. About 32 days a year reach 90° and 5 reach 100° (Rapid City Rgnl Airport).
When is the first and last frost in Green Valley?
In half of years the last spring frost (32°) comes by May 12 and the first fall frost by October 1, about 139 frost-free days, at Rapid City Rgnl Airport.
What growing zone is Green Valley in?
Zone 5a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −15°.
What is the best time of year to visit Green Valley?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Green Valley getting warmer?
Yes: 1991–2020 averaged 1.4° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 56% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Green Valley.
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.