Retail natural gas utility rates in Colorado will increase by 14-17% in the first quarter compared to the same period this year, Minnesota-based Xcel Energy said. The combination utility’s electric utility rates will drop slightly quarter over quarter.

The proposed rate changes are set to be effective Jan. 1, pending approval from the Colorado Public Utilities Commission.

“Natural gas prices were higher than expected at the onset of the winter heating season and continue to he higher,” Xcel said. As a result, residential and small business customers face increases in the 14-17% range.

For residential customers, on average the same bill that was nearly $72/month in the first quarter this year is projected to be $81.58/month in the first quarter of 2014, Xcel estimated. For small businesses the change in average monthly bills is from $290/month to $338/month.

Electric charges for both residential and small businesses decrease less than 1% quarter over quarter, staying essentially flat at just under $69/month for residential customers and at the $113/month level for small businesses.

The latest rate changes are part of quarterly filings made by Xcel, applying gas cost and electric commodity adjustments.

For residential gas customers the rate-per-therm increased from 43.3 cents/therm in the first quarter this year to 51.3 cents/therm in the same period next year; the change for small businesses was from 42.95 cents/therm to 50.98 cents/therm in the upcoming 1Q2014.