South Dakota’s weather really swings from one extreme to the other. One month you’re shivering in bitter cold, and a few months later, you’re sweating in the summer heat. The state sits smack in the middle of the Great Plains, so it gets those wild continental climate patterns—big temperature jumps and unpredictable rain from month to month.
South Dakota hits its coldest temperatures in January and February, usually between -5°C and 5°C. The warmest months are July and August, when temps can climb to 27°C or even 32°C. Knowing these monthly patterns is pretty helpful, whether you’re bracing for a blizzard or planning a summer picnic.
This guide breaks down South Dakota’s weather, month by month. We’ll look at temperature trends, rainfall, and what each season feels like. You’ll get a sense of when the weather’s at its best, how rain changes through the year, and what to expect if you’re in Sioux Falls or elsewhere.
Overview of South Dakota’s Monthly Weather Patterns
South Dakota’s continental climate brings four distinct seasons, which means you’ll see big temperature swings all year. Its spot in the Great Plains, plus the Missouri River cutting through, really shapes the weather.
General Climate Zones
South Dakota has a humid continental climate—hot summers, cold winters. The average elevation hovers around 533 meters above sea level.
Yearly, the average temperature lands at 10.25°C (50.45°F). In the north, like Aberdeen, winter lows can hit -15°C, but out west near Rapid City, summer highs can touch 30°C.
Because South Dakota sits far from big lakes or oceans, nothing really moderates the climate. That’s why the seasons feel so different and why weather can change in a blink.
Wind is pretty much a constant companion here. Depending on the season and where you are, average wind speeds run between 12 and 21 kph.
Seasonal Changes
Winter (December-February) brings the coldest stretch. Temperatures range from -15°C up to 5°C. January usually feels like the dead of winter.
Snow shows up regularly in winter. Aberdeen averages about 60mm of snow each month, while Rapid City gets less, close to 35mm.
Spring (March-May) warms up fast. March starts at around 6°C, but by May, you can see 21°C in many places. Rain picks up too—May brings 65-75mm of precipitation.
Summer (June-August) is when things heat up. July hits 29-30°C in most cities. Rainfall peaks, and June can see 80-90mm statewide.
Fall (September-November) cools things down again. September starts at about 23°C, but by November, it’s closer to 5-8°C. Rain falls off, and snow starts creeping back in late fall.
Variations Across Regions
The Missouri River really splits the state into two climate zones. Eastern South Dakota gets more humidity and rain than the west.
Eastern South Dakota (think Sioux Falls) sees more rainfall all year. Summer months can bring over 90mm of rain. It also feels muggier—July can have 11 humid days.
Western South Dakota (like Rapid City) stays drier and less humid. Rainfall is lower here, with summer months getting only 40-60mm. You’ll see fewer muggy days and more clear skies.
East and west don’t differ much in temperature, though. Western spots like Rapid City have slightly warmer winter lows, but summer highs are pretty similar.
Aberdeen, up north, feels the harshest winter cold. January lows drop to -15°C.
Monthly Temperature Averages
South Dakota’s temperature swings are no joke. Winter lows drop far below freezing, and summer highs reach into the mid-80s (Fahrenheit). Each of the state’s three main climate zones—Sioux Falls, Rapid City, and Aberdeen—has its own quirks.
Average Highs by Month
Winter months bring the lowest highs. In January, Sioux Falls averages 27°F, Rapid City hits 37°F, and Aberdeen sits at 24°F.
February warms up a bit—highs reach 32°F in Sioux Falls, 40°F in Rapid City, and 29°F in Aberdeen. March starts to feel like spring, with highs at 45°F in Sioux Falls, 49°F in Rapid City, and 42°F in Aberdeen.
Spring and early summer bring quick warmups. April averages 60°F in Sioux Falls, 59°F in Rapid City, and 59°F in Aberdeen. May goes further, with highs at 71°F in Sioux Falls, 68°F in Rapid City, and 70°F in Aberdeen.
Peak summer hits in July and August. July reaches 84°F in Sioux Falls and Aberdeen, and 86°F in Rapid City. August stays hot—81°F in Sioux Falls, 85°F in Rapid City, and 82°F in Aberdeen.
Average Lows by Month
Winter lows are just brutal statewide. January brings average lows of 10°F in Sioux Falls, 18°F in Rapid City, and a frigid 6°F in Aberdeen.
February gets a little better—lows of 15°F in Sioux Falls, 20°F in Rapid City, and 11°F in Aberdeen. Winter really tests your tolerance for the cold.
Spring nights get less harsh. March averages 26°F in Sioux Falls, 27°F in Rapid City, and 23°F in Aberdeen. By April, lows rise to 38°F in Sioux Falls, 36°F in Rapid City, and 35°F in Aberdeen.
Summer nights offer some relief. July nights average 64°F in Sioux Falls, 61°F in Rapid City, and 61°F in Aberdeen. August stays comfortable—lows around 58°F to 61°F across the state.
Monthly Temperature Trends
Rapid City often has the warmest winter highs because of its western location and elevation. In January, it averages 37°F, warmer than the eastern cities.
Aberdeen gets the worst of winter. January lows drop to 6°F—colder than Sioux Falls or Rapid City.
Temperature ranges can be wild. Winter days swing 15-20 degrees, while summer ranges are a bit more moderate, about 20-25 degrees between highs and lows.
The growing season runs from late April through October. During this time, temperatures usually stay above freezing, which is great for agriculture.
Precipitation Throughout the Year
South Dakota gets most of its rain in late spring and early summer. Snow piles up in winter and early spring. Wet and dry periods are pretty distinct—summer brings thunderstorms and quick showers.
Rainfall Patterns by Month
Rainfall follows a seasonal rhythm. The wettest stretch is May through August. June usually brings the most rain—Sioux Falls gets 3.7 inches, Aberdeen 3.2 inches.
March starts off slow—Sioux Falls sees just 0.9 inches, and Rapid City barely gets 0.3 inches. April kicks off the wet season, with Sioux Falls jumping to 2.2 inches.
Summer keeps the rain coming. July and August both bring about 2.6 inches to most cities. In September, rain starts to taper off—Sioux Falls gets 2.5 inches.
Winter is dry. December through February rarely bring more than 0.2 inches of rain. Rapid City sometimes gets nothing measurable at all.
The number of rainy days jumps around too. Summer averages 9-11 days with rain. Winter? Only 1-2 days a month.
Monthly Snowfall Averages
Snow falls from October through April. The heaviest comes in winter, with December usually seeing the most.
December leads the way—Sioux Falls averages 2.8 inches, Aberdeen 2.5 inches. Rapid City, being farther west, gets less at 1.4 inches.
January and February keep the snow coming. Sioux Falls gets 2.0 inches in January, 2.3 in February. Aberdeen is similar—2.1 and 2.4 inches.
Spring snow tapers off but doesn’t vanish. March brings 2.4-2.6 inches in most cities. April still sees 1.7-2.5 inches, depending on where you are.
By May, snow is rare—cities get just 0.1-0.7 inches. From June through September, snow’s off the table.
October marks the start of snow again. Most places see 0.2-0.7 inches as winter creeps back.
Thunderstorms and Showers
South Dakota’s thunderstorm season hits hardest in late spring and summer. These storms dump heavy rain and bring lots of afternoon showers.
May is when storms really ramp up. Warm, humid air clashes with cooler air, setting the stage for severe weather.
June and July see the most thunderstorm action. Afternoon and evening showers pop up all over. These storms can dump a lot of rain in a hurry, making up a big chunk of the monthly totals.
Most thunderstorms fire up in the afternoon. Rising temps make the air unstable, and that’s when showers get going.
August still sees storms, but not as many as earlier in the summer. By September, thunderstorm activity drops off noticeably.
Storm frequency depends on where you are. Sioux Falls and the east get more storms than the west. That’s why eastern South Dakota is rainier in summer.
Cloud Cover and Sunshine
South Dakota’s cloud cover and sunshine shift a lot by season. Some months bring clear skies, while others are socked in with clouds.
Partly Cloudy Days
Spring and fall bring the most partly cloudy days, with 30% to 70% of the sky covered.
Spring often feels unsettled, with clouds building up, especially in April and May.
Summer tends to be more all-or-nothing—either clear or pretty overcast.
Fall goes back to more mixed skies. September and October often bring a blend of sun and clouds as the weather changes.
In winter, partly cloudy days usually come with snow systems. Cloudy skies often mean light snow or just gray, overcast days.
Clear and Overcast Periods
Clear stretches are most common in summer, when high pressure settles in.
July and August can string together several sunny days. You’ll get plenty of bright, cloudless weather.
Winter, on the other hand, tends to be gloomy. December through February often bring long runs of overcast skies as low pressure systems roll through.
Spring’s cloudy spells usually tag along with storm systems. March and April can have several days of gray skies before things clear up.
Eastern South Dakota gets more overcast days than the west. Moisture and terrain both play a role.
Sunlight Hours by Season
Summer brings the most sunshine—over 9.6 hours a day in some spots. June and July are the sunniest months.
Winter cuts daylight way down. December and January have the least sunshine.
Spring and fall sit in the middle, with daylight hours gradually ramping up or winding down.
Sunshine totals aren’t the same everywhere. Western areas near the Black Hills sometimes see different patterns because of the hills and higher ground.
How much sun you get each month really depends on how many storms roll through and how clouds build up.
Highlight: Weather in Sioux Falls
Sioux Falls has a continental climate—warm, sometimes hot summers up to 85°F, and freezing winters that can drop to 10°F. Winters here are snowy and windy from December through February. Summers feel great for getting outside.
Monthly Climate Charts
Sioux Falls follows a clear seasonal rhythm. July is the hottest, with daytime highs around 85°F. January nights can fall to 10°F or even lower.
Extremes are rare—temps almost never go above 94°F or below -11°F. Spring and fall bring milder weather, somewhere between those extremes.
Temperature Ranges by Season:
- Winter (Dec-Feb): 10°F to 30°F
- Spring (Mar-May): 35°F to 65°F
- Summer (Jun-Aug): 60°F to 85°F
- Fall (Sep-Nov): 40°F to 70°F
Rain falls year-round, but summer gets the most. In winter, snow covers the ground for months at a time.
Unique Weather Characteristics
Sioux Falls sits in a region where the weather changes quickly. You’ll notice partly cloudy skies most of the year instead of long stretches of clear or overcast days.
Winter winds really make the cold bite harder than the thermometer says. From December through February, travelers and locals face some tough outdoor conditions.
The city’s spot in the Great Plains means weather systems roll in from all directions. Cold air drops down from Canada and collides with warm, moist air from the Gulf of Mexico.
Key Weather Features:
- Strong winter winds
- Rapid temperature swings
- Variable spring conditions
- Humid summer weather
Notable Weather Events
Sioux Falls deals with a range of severe weather every year. Blizzards hit during the winter, dumping heavy snow and bringing brutal wind chills.
Spring and early summer ramp up the tornado risks. The city sits at the northern edge of Tornado Alley, where storms can bring big hail and damaging winds.
Ice storms sometimes sweep through in winter and early spring. These make roads slick and can knock out power.
Flooding pops up during spring snowmelt or after heavy summer rains. The Big Sioux River runs through town and sometimes spills over its banks.
Heat waves roll in during the summer. When temperatures stay above 90°F for days, cooling systems get pushed to the limit and vulnerable folks need to take extra care.
Best and Worst Months to Visit South Dakota
South Dakota brings something different every season. Summer usually gives you the best shot at comfortable weather for outdoor plans, while winter can really test travelers. The state’s continental climate means you’ll notice clear shifts between the best and toughest times to visit.
Ideal Weather Periods
June through August is when South Dakota shines for visitors. These months bring the warmest weather, with highs in the upper 60s to low 80s°F.
July stands out as the hottest month, ranging from 60°F to 87°F. August is pretty similar, so both months are great for exploring outside.
May and September act as pleasant shoulder seasons. May runs from 44°F to 70°F, and September cools a bit to 47°F to 74°F.
Perks of these months include:
- Fewer crowds at main attractions
- Good hiking weather
- May’s spring flowers
- September’s fall colors
Summer brings the most rain, with June averaging 3.6 inches. Still, the warmth usually makes the showers easier to handle than in colder months.
Challenging Weather Months
December through February makes visiting tough. January hits the coldest, with temperatures between 7°F and 26°F.
Winter brings:
- Frequent snow and ice
- Short days
- Strong winds, especially up north and out west
- Some outdoor spots become hard to reach
March and November bring unpredictable weather as the seasons shift. March runs from 21°F to 43°F, and late snowstorms aren’t rare.
November cools off fast, dropping from 22°F to 42°F as winter creeps in. Both months can throw in a sudden weather twist.
April isn’t always easy either, with temps between 32°F and 57°F and the chance for late snow—especially in higher spots.
Considerations for Travelers
Summer visitors should toss sunscreen and a few layers into their bags, since temperatures swing a lot between day and night. Thunderstorms pop up pretty often during peak season, so packing some waterproof gear makes life easier.
Winter travelers really need heavy insulation—think thermal layers, thick coats, and solid boots. Icy roads can slow you down, so plan for extra travel time and just be careful out there.
Shoulder season visitors get the wild card. Spring and fall sometimes surprise you with unpredictable weather, but those seasons can hand you some of the best photo ops if you stay flexible.
If you’re watching your budget, you’ll probably spot better accommodation rates during the off-peak months. Just keep in mind, some attractions cut their hours or even shut down completely in the winter.
Weather flips fast across South Dakota’s landscape. The Black Hills might throw something totally different at you than the eastern prairie, so you’ll want to plan for wherever you’re headed.