DES MOINES, I.A.(WNAX)- It’s been a volatile year for natural gas prices.

Geoff Greenwood with Mid-American Energy says while supply has been steady, they expect prices to bounce up and down the rest of winter.

Greenwood says they do lock in prices on a portion of their gas supply in the fall.

Greenwood says the open market prices change almost hourly.

Natural gas prices have dropped from over six dollars a therm in late January to under four dollars this week.

Mid-American serves about one hundred four thousand customers in southeast South Dakota.