Roy Lake, SD Climate: Temperature & Rain by Month
Temperature and precipitation from NOAA NCEI 1991–2020 normals →, plus PlainClimate's derived comfort score
30-year climate normals (1991-2020) from Roy Lake's primary NOAA station, ROY LAKE.
The climate verdict for Roy Lake
Winter sets the terms in Roy Lake, South Dakota. A pronounced 59.9°F seasonal swing and heating demand above twice the cooling total frame an annual average of 44°F. At 49/100 (moderate) the climate comfort score falls in the bottom third of the station-mapped U.S. score corpus, exceeding only 18% of scores.
- 44°F
- yearly average temperature, NOAA normal
- 49/100
- comfort score, above 18% of station-mapped location scores
- 25.0"
- annual precipitation · 48" snow
- 160 days
- frost-free growing season
Roy Lake: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00397326 · Roy Lake, SD 44°F mean · 25.0" precip
TEMP-COOL · RANK-COOL · PHOTO-FINISH · PRCP-DRY · SWING-WIDE · COMF-LOW · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 44°F
- RANK-COOL #892
- PHOTO-FINISH ≈ Conde
- PRCP-DRY 25.0"
- SWING-WIDE 60°F
- COMF-LOW 49/100
- LOAD-HEAT 8,417 HDD
- STN-1 USC00397326
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Conde, SD (+ 0.1 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every SD station list.
- Roy Lake (this station) 44°F
- Hot Selby, SD 44°F
- Near Conde, SD 44°F
- Near Benson, MN 44°F
- Cold Breien, ND 43°F
Climate Living Index · Roy Lake
Roy Lake: 31/100 · grade F
Roy Lake publishes 5 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 1 missing weight rescale to 100.
PlainClimate-derived for Roy Lake, not an official NOAA rating. Rankings still use Comfort Score 49/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Precipitation balance | 25.0 in · 10.0 from 35 in | 65/100 · C |
| Frost-free season | 160 days/year | 33/100 · F |
| Normal heat + freeze calendar | 171 calendar days | 31/100 · F |
| Snowfall burden | 48.1 inches/year | 22/100 · F |
| Annual temperature balance | 43.5°F · 24.0° from 67.5°F | 14/100 · F |
Roy Lake · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Roy Lake is a continental Köppen climate: Dfa
Coldest-month mean 12.1°F and warmest-month mean 72.0°F place this station in continental, no dry season, hot summer climates (Dfa). Class Dfa is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: continental, specifically continental, no dry season, hot summer.
- Köppen code
- Dfa
- Group
- Continental
- Warmest month
- 72.0°F
- Coldest month
- 12.1°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · heating-led station
Where Roy Lake sits across the climate record
Three NOAA fields for Roy Lake's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- Cooler than 87%
- Among 6,861 stations, Roy Lake sits in the cooler third of annual means.
- Annual precipitation
- 34th percentile wetness
- Neither arid nor torrential versus 6,352 station totals.
- Seasonal temperature swing
- Wider than 98%
- Warmest-to-coldest month gap for Roy Lake is large versus 6,861 complete station-years.
How Roy Lake compares across U.S. station-mapped locations
Roy Lake's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
49 18th percentile score exceeds 18% of 6,189 station-mapped location scores
- 0–10: 0 station-mapped locations (0%). Below this entry.
- 10–20: 0 station-mapped locations (0%). Below this entry.
- 20–30: 96 station-mapped locations (2%). Below this entry.
- 30–40: 280 station-mapped locations (5%). Below this entry.
- 40–50: 1,113 station-mapped locations (18%). This entry sits in this band.
- 50–60: 1,329 station-mapped locations (21%). Above this entry.
- 60–70: 1,236 station-mapped locations (20%). Above this entry.
- 70–80: 650 station-mapped locations (11%). Above this entry.
- 80–90: 921 station-mapped locations (15%). Above this entry.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Snow | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|---|
| January | 22°F (-6°C) | 3°F (-16°C) | 12°F (-11°C) | 0.6" | 6.6" | 30.9 | 0.0 |
| February | 26°F (-4°C) | 5°F (-15°C) | 15°F (-9°C) | 0.6" | 9.2" | 27.8 | 0.0 |
| March | 38°F (3°C) | 18°F (-8°C) | 28°F (-2°C) | 1.0" | 7.0" | 28.5 | 0.0 |
| April | 53°F (12°C) | 32°F (0°C) | 42°F (6°C) | 2.1" | 7.2" | 16.4 | 0.0 |
| May | 67°F (19°C) | 46°F (8°C) | 56°F (14°C) | 3.1" | 0.2" | 3.2 | 0.2 |
| June | 76°F (25°C) | 58°F (14°C) | 67°F (19°C) | 4.3" | 0.0" | 0.0 | 0.2 |
| July | 82°F (28°C) | 62°F (17°C) | 72°F (22°C) | 4.4" | 0.0" | 0.0 | 1.9 |
| August | 81°F (27°C) | 60°F (16°C) | 70°F (21°C) | 2.6" | 0.0" | 0.0 | 1.3 |
| September | 72°F (22°C) | 51°F (11°C) | 61°F (16°C) | 2.5" | 0.0" | 0.5 | 0.1 |
| October | 57°F (14°C) | 37°F (3°C) | 47°F (8°C) | 2.2" | 2.5" | 11.2 | 0.0 |
| November | 40°F (5°C) | 23°F (-5°C) | 32°F (0°C) | 0.8" | 4.3" | 24.9 | 0.0 |
| December | 27°F (-3°C) | 10°F (-12°C) | 18°F (-8°C) | 0.8" | 11.1" | 30.9 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 83°F around July 22, short of 90°F on every date, while 171 dates carry a normal low at or below freezing, the coldest 2°F near January 22.
The freezing stretch
The normal low stays at or below 32°F into April 15, then returns to freezing around October 28, covering 171 dates in all.
Derived from the normal daily minimum. This is a different measure from the 50%-probability frost dates shown elsewhere on this page, which come from NOAA’s frost product.
Where the wet dates fall
The likeliest wet date is June 12, when 37% of years recorded at least a hundredth of an inch. The driest is November 21 at 14%. Summed across the calendar, that is about 85 wet dates a year.
The widest day
May 1 carries the biggest normal gap between afternoon and dawn, 22°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Roy Lake.
Where Roy Lake Stands Nationally
Days and nights track unusually close together; the widest normal swing, about 22°F, is narrower than most stations record.
Roy Lake earns one nationally notable standing (outer quintile) against 6,860 NOAA 1991–2020 normals stations, middle-of-the-pack metrics stay silent here.
Monthly Precipitation
Average monthly rainfall and snowfall
Snow: 6.6"
5.0 days with precipitation
Snow: 9.2"
5.1 days with precipitation
Snow: 7.0"
4.9 days with precipitation
Snow: 7.2"
6.9 days with precipitation
Snow: 0.2"
10.6 days with precipitation
11.2 days with precipitation
8.5 days with precipitation
7.9 days with precipitation
7.6 days with precipitation
Snow: 2.5"
7.2 days with precipitation
Snow: 4.3"
3.8 days with precipitation
Snow: 11.1"
5.5 days with precipitation
Roy Lake runs a summer-peaked wet season
45% of Roy Lake's yearly precipitation falls in June, July and August alone, against the 25% an evenly spread year would give those three months. The wettest month is July at 4.4", on a wide 59.9°F gap between its warmest and coldest month. Warm-season convection and, across the Southwest, the North American monsoon produce this shape: rain arrives in short heavy bursts during the hottest part of the year rather than as long cool-season soaking.
- Wettest three months: July, June, May, taking 47% of the annual total between them.
- Driest month: January at 0.6".
- Winter share: 8% falls in December, January and February.
Shares are computed from this station's own 1991-2020 monthly precipitation normals. A summer-peaked label means the June-August share reaches 35%; it describes timing across an average year, not any single season, and says nothing about how heavy an individual storm can be.
How Roy Lake's precipitation splits across the calendar
About 84 days a year record measurable precipitation here, carrying 25.0" between them, or roughly 0.30 inches on a typical wet day. That sits in the middle band: neither the many-light-days pattern of the Pacific Northwest and the Great Lakes, nor the few-heavy-events pattern of the Gulf and the desert Southwest.
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year and say nothing about the heaviest single storm on record.
Winter brings real snow to Roy Lake
Roy Lake averages 48.1 inches of snowfall a year, with December the snowiest month on the normals, spread across roughly 24 days that record measurable snow. That is depth accumulating on the ground, which is why it can exceed the annual precipitation figure: precipitation counts the liquid the snow melts down to, and fresh snow is mostly air.
- Annual snowfall: 48.1 inches of depth.
- Days recording measurable snow: about 24 a year.
- At a rough ten-to-one melt ratio, snow accounts for on the order of 19% of the year's precipitation.
NOAA 1991-2020 normals. The ten-to-one ratio is a convention, not a measurement: real ratios vary with temperature, so treat the share as an order of magnitude rather than an exact split.
Frost Dates & Growing Season
First Fall Freeze
October 9
50% probability date
Last Spring Freeze
May 2
50% probability date
Growing Season
160 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
8,417
Higher = more heating needed
Cooling Degree Days
619
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
Nationwide similar cities
Other rankable U.S. places outside SD closest to Roy Lake on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (44°F here).
- Alpena, MI 44°F · 0.0°F off
- Amery, WI 44°F · 0.0°F off
- Blanca, CO 44°F · 0.0°F off
- Bynum, MT 44°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (25.0" here), excluding temperature-peer places.
- Wingate, TX 25.0" · 0.0" off
- Alta, WY 25.0" · 0.0" off
- Dilley, TX 25.0" · 0.0" off
- Iliamna, AK 25.0" · 0.0" off
Snow and freeze rhythm
When cold and snow define Roy Lake
heating led · moderate · high swing
Winter and seasonal range jointly define this record. Roy Lake logs 8,417 heating degree days, more than twice its 619 cooling total, while the typical coldest-to-warmest-month gap reaches 59.9°F. The annual mean therefore compresses two materially different seasons.
Roy Lake's frost-free season lasts about 160 days, a middle-length window whose endpoints matter more than the annual average. It describes freeze probability, not year-specific planting conditions.
-
1. Roy Lake coldest normal
January
Averaging 12°F (-11°C), this month sits below freezing for the month as a whole, not merely overnight.
-
2. Roy Lake typical freeze period
January through December
The station reports average freezing days from January through December.
-
3. Roy Lake snow peak
December
Roy Lake averages 48.1 inches of snow a year, with December the snowiest month on the normals.
Questions about Roy Lake's climate
How much snow does Roy Lake get? ▼
How cold does Roy Lake get in winter? ▼
How much energy does heating and cooling require in Roy Lake? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Roy Lake's primary station: ROY LAKE (USC00397326). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The conservative exact name-and-state crosswalk finds no Census place match, so PlainClimate treats this as a station-mapped location and does not claim it is a municipality. No exact Gazetteer row for Roy Lake; facility counts that depend on place identity are therefore an upper bound, not a municipal census.
On this page every temperature, precipitation, and derived score for Roy Lake comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.