Is This Really South Dakota?

OK, I am confused. Today, Janine and I walked outside for our afternoon walk. Half way around on our route, we had to take our coats off. The sun was beating down on our backs on the last leg, which is part up hill. The sun felt warm. The air felt balmy with little breeze. Got back to my desk. The calendar still said January 5th! Sure hard to believe it is January! Is this really South Dakota?