Rescue crews called off the search tonight for a South Dakota man who is missing on the Missouri River, but will be back out Sunday morning.

Crews are looking for 46-year-old Michael Larson of Yankton.  Bon Homme County Emergency Management says they began the search Friday night, after a fisherman found an empty boat on a sandbar near the town of Running Water.

May's fluctuating weather conditions can make a search operation challenging for crews.  And Saturday's below-normal temperatures and strong winds didn't make for pleasant conditions on the river.

"It's never an easy situation," Mark Johnson, Director of Yankton County Search and Rescue said.

For agencies in both South Dakota and Nebraska, searching for missing boater Michael Larson is no simple task.

"It's a little cooler than we'd like it if we're going to be in the water," Johnson said. "Of course, we're going to be along the edges of the water. You're going to get wet. You're going to get a little cool."

Johnson says the conditions aren't ideal, but they're not anything teams can't handle.

"There are different types of missions - some water, some land," Johnson said.  "We've had a variety of different situations we've been in."

Around 7:00 AM Saturday morning, crews were out in 37-degree weather, about ten degrees below average. And wind speeds weren't kind either, with some winds gusting up to 30 miles per hour in some spots. But crews say they're prepared for the changing conditions.

"The main thing we want to do is make sure that we stay safe and keep our people safe and able to continue the search as long as possible," Johnson said.

Jeremy Dangel with Yankton County Emergency Management says they've been out in rougher conditions.

"It seems like the season's starting a little earlier this year than it normally does, but we've done this many times before," Dangel said.

For now, the challenges mother nature throws at searchers aren't enough to keep them out of the river and searching for Larson.

"Our goal is just to continue the search until we do find what we are looking for," Johnson said.

"We're here to help, and hopefully come to a speedy and as positive as possible resolution," Dangel added.