Roslyn Auditorium · Photo: Wtshymanski · CC BY 3.0Few U.S. towns have colder winter nights than Roslyn
Midsummer highs settle at about 80°. The wettest month is June; the driest is January. By July afternoons alone, it runs cooler than 91% of U.S. towns. Warm coats and heating bills mark the months from October to April, when means dip under 50°.
A year in Roslyn at a glance
Each month’s typical high and low, and what it brings.
What stands out about Roslyn’s climate
Compared with towns across the U.S., with Roslyn’s place in South Dakota beside it.
What a year in Roslyn feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 164 frost-free days a year
In half of years the last 32° night comes by May 1 and the first by October 12. Frost and day counts come from NOAA’s station at Waubay Natl Wild Life, SD, 9 miles from the town’s center, at about the same height.
The 2023 USDA map puts Roslyn’s center in zone 4b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −24°. 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 43 inches of snow a winter
Snow, measured at Webster, SD, falls mostly in January. Precipitation (rain plus melted snow) adds up to 24 inches a year; June is the wettest month and January the driest. Rain or snow falls on about 77 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Roslyn
93% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through May.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Waubay Natl Wild Life, SD.
Living with Roslyn’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
164 frost-free days in zone 4b. The last frost comes by May 1 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 12.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August and September.
Parks & trails →Cold waves are 33% of the yearly building losses FEMA expects in Roslyn from natural hazards, the largest share. Normals are averages; the hazards page covers the extremes.
Natural hazards →Roslyn and its neighbors
Every town next door is within a degree of Roslyn in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Roslyn’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 |
|---|---|---|---|---|
| Roslyn, SD | 1° | 80° | 24" | 43" |
| Crookston, MN | −2° | 81° | 23" | 50" |
| Grand Forks, ND | −2° | 81° | 22" | 49" |
| Kingsford, MI | 5° | 80° | 29" | 61" |
| Rice Lake, WI | 3° | 80° | 33" | 53" |
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 Roslyn averaged 1.0° warmer than the 1900s. The biggest change is in January (+2.7°).
A smaller shift than in 76% 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 Roslyn compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Roslyn’s place among South Dakota’s.
Roslyn weather by month
Highs, lows and precipitation from NOAA’s grid at Roslyn’s center; snow, wet days and snow on the ground from Webster, SD. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 20° | 1° | 0.7" | 9.6" | 5 | −3° – 23° |
| February | 24° | 5° | 0.7" | 7.9" | 4 | 0° – 26° |
| March | 37° | 18° | 1.0" | 5.1" | 4 | 18° – 42° |
| April | 52° | 30° | 2.0" | 5.0" | 6 | 31° – 50° |
| May | 66° | 44° | 3.1" | 0.0" | 10 | 50° – 61° |
| June | 75° | 55° | 3.9" | 0.0" | 10 | 60° – 69° |
| July | 80° | 59° | 3.8" | 0.0" | 9 | 61° – 76° |
| August | 79° | 57° | 2.5" | 0.0" | 7 | 63° – 71° |
| September | 71° | 48° | 2.5" | 0.0" | 7 | 53° – 64° |
| October | 55° | 34° | 2.3" | 1.4" | 6 | 36° – 49° |
| November | 38° | 20° | 0.7" | 6.0" | 4 | 17° – 40° |
| December | 25° | 8° | 0.7" | 7.8" | 5 | 2° – 24° |
| Year | 52° | 32° | 23.9" | 42.8" | 77 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 0° to 26°. August is the most reliable, staying within 9°.
Where Roslyn’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 Roslyn’s center.
- Snow: Webster, SD.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Waubay Natl Wild Life, SD, 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 Roslyn’s climate
What is the weather like in Roslyn?
A typical July afternoon reaches 80°, a January night drops to 1°, and about 43 inches of snow falls in a normal winter. Colder January nights than all but 71 U.S. towns; cooler July afternoons than 91% of U.S. towns.
How cold does it get in Roslyn in winter?
January nights average 1°. About 166 nights a year reach 32° or below and 36 reach 0° or below. In the coldest January of the last 30 years the month averaged −3°.
How much snow does Roslyn get?
About 43 inches in a normal winter at Webster, SD, most of it in January.
How hot does it get in Roslyn?
July, with a typical high of 80° and a low of 59°. About 5 days a year reach 90° (Waubay Natl Wild Life, SD).
When is the first and last frost in Roslyn?
In half of years the last spring frost (32°) comes by May 1 and the first fall frost by October 12, about 164 frost-free days, at Waubay Natl Wild Life, SD.
What growing zone is Roslyn in?
Zone 4b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −24°.
What is the best time of year to visit Roslyn?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Roslyn getting warmer?
Yes: 1991–2020 averaged 1.0° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 76% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Roslyn.
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.