From Meteorologist Ethan Emery:

A windy and wet Sunday forecast:

Tonight will see clouds increasing from the west as temperatures dip down in the 30s for most; though some 40s are possible in the South Dakota plains. Moisture will move in around midnight and be a rain/snow mix in northeast Wyoming though it could go to all snow before sunrise on Sunday. If anyone sees moisture in the Black Hills, it will be in the form of snow. Travelers on Sunday morning should be cautious in Wyoming and the Hills as roads could be slushy in a few spots. Remember that overpasses and bridges will get icy before roads on the ground do!

Sunday will see a low pressure move into the area and deliver winds and moisture! It will mainly be rain in the South Dakota plains, though some snow may mix in the evening hours. Snow in Wyoming looks to transition back to rain during the day on Sunday and then go back to snow briefly before things dry out late Sunday night. Accumulations look light for most spots, though folks in the Central and Northern Hills in places above 5,000 feet elevation could see totals between 3"-5" with isolated higher amounts possible. The Northern Hills specifically above 5,500 feet elevation will see the highest amounts between 5"-8" with locally higher amounts. The bigger impact will be the winds as winds will be sustained between 25-40 mph with gusts up to 60 mph possible! Take those decorations inside and if you're traveling, make sure to grip that steering wheel extra tight!

Extended forecast:

Monday will be dry with partly cloudy skies, but it will still be breezy as high pressure pushes in from the north and west. Tuesday will see temperatures rebound into the 50s for many spots, though this will be short lived as moisture returns Tuesday night into Wednesday with cooler conditions. Then things look to stay dry from Thursday through Saturday as temperatures climb back up in the 50s for the start of next weekend, though long-range computer models indicate that temperatures will drop once again as another system will move in next Sunday. We will keep an eye on it and update the forecast as needed on here, on the air and on our mobile weather app!

Downtown Rapid City Climate Report