Gregory County State Bank · Photo: Ammodramus · CC0January in Fairfax bites harder than in 90% of U.S. towns
High summer brings afternoon highs near 87°. It is a dry place: less rain and snow fall here than on 87% of U.S. towns. The latest 30-year average runs 0.8° warmer than 1901–2000’s, with January up the most. Tender plants can go out after about May 3; in half of years the first frost comes by October 10.
A year in Fairfax at a glance
Each month’s typical high and low, and what it brings.
What stands out about Fairfax’s climate
Compared with towns across the U.S., with Fairfax’s place in South Dakota beside it.
What a year in Fairfax feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 159 frost-free days a year
In half of years the last 32° night comes by May 3 and the first by October 10. Frost and day counts come from NOAA’s station at Bonesteel, SD, 5 miles from the town’s center, at about the same height.
The 2023 USDA map puts Fairfax’s center in zone 5a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −16°. 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 37 inches of snow a winter
Snow, measured at Bonesteel, SD, falls mostly in April. Precipitation (rain plus melted snow) adds up to 26 inches a year; May is the wettest month and January the driest. Rain or snow falls on about 62 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Fairfax
90% 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 Bonesteel, SD.
Living with Fairfax’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
159 frost-free days in zone 5a. The last frost comes by May 3 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 10.
Months with highs of 62–84° and lows of 40° or more: May, June, August and September.
Parks & trails →Cold waves are 43% of the yearly building losses FEMA expects in Fairfax from natural hazards, the largest share. Normals are averages; the hazards page covers the extremes.
Natural hazards →Fairfax and similar climates
TownRatings has no climate map of the towns around Fairfax yet.
Climates most like Fairfax’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 |
|---|---|---|---|---|
| Fairfax, SD | 13° | 87° | 26" | 37" |
| Hastings, NE | 15° | 87° | 27" | 29" |
| Council Bluffs, IA | 14° | 87° | 33" | 27" |
| Air Force Academy, CO | 14° | 84° | 21" | 55" |
| Providence, UT | 15° | 89° | 19" | 44" |
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 Fairfax averaged 0.8° warmer than the 1900s. The biggest change is in January (+2.9°).
A smaller shift than in 91% 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 Fairfax compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Fairfax’s place among South Dakota’s.
Fairfax weather by month
Highs, lows and precipitation from NOAA’s grid at Fairfax’s center; snow, wet days and snow on the ground from Bonesteel, SD. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 31° | 13° | 0.5" | 5.5" | 3 | 15 | 15° – 37° |
| February | 36° | 16° | 0.7" | 5.9" | 4 | 11 | 13° – 36° |
| March | 47° | 25° | 1.3" | 5.5" | 5 | 9 | 26° – 50° |
| April | 58° | 35° | 3.0" | 7.7" | 7 | 3 | 39° – 53° |
| May | 70° | 46° | 4.0" | 0.0" | 9 | 0 | 53° – 64° |
| June | 80° | 57° | 3.8" | 0.0" | 8 | 0 | 64° – 73° |
| July | 87° | 62° | 3.2" | 0.0" | 7 | 0 | 66° – 82° |
| August | 84° | 61° | 3.1" | 0.0" | 5 | 0 | 67° – 76° |
| September | 76° | 52° | 2.6" | 0.0" | 4 | 0 | 59° – 70° |
| October | 62° | 38° | 2.1" | 2.0" | 5 | 1 | 42° – 55° |
| November | 47° | 26° | 0.9" | 6.9" | 4 | 8 | 26° – 45° |
| December | 34° | 16° | 0.7" | 3.7" | 3 | 13 | 14° – 31° |
| Year | 59° | 37° | 25.9" | 37.2" | 62 | 61 |
How much a month can swing
A normal is an average. March swings the most: from 1991 to 2020 its average ranged from 26° to 50°. August is the most reliable, staying within 10°.
Where Fairfax’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 Fairfax’s center.
- Snow: Bonesteel, SD.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Bonesteel, SD, 5 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 Fairfax’s climate
What is the weather like in Fairfax?
A typical July afternoon reaches 87°, a January night drops to 13°, and about 37 inches of snow falls in a normal winter. Colder January nights than 90% of U.S. towns; hotter July afternoons than 59% of U.S. towns.
How cold does it get in Fairfax in winter?
January nights average 13°. About 162 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 15°.
How much snow does Fairfax get?
About 37 inches in a normal winter at Bonesteel, SD, most of it in April, with snow on the ground about 61 days a year.
How hot does it get in Fairfax?
July, with a typical high of 87° and a low of 62°. About 26 days a year reach 90° and 3 reach 100° (Bonesteel, SD).
When is the first and last frost in Fairfax?
In half of years the last spring frost (32°) comes by May 3 and the first fall frost by October 10, about 159 frost-free days, at Bonesteel, SD.
What growing zone is Fairfax in?
Zone 5a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −16°.
What is the best time of year to visit Fairfax?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Fairfax getting warmer?
Yes: 1991–2020 averaged 0.8° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 91% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Fairfax.
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.