( Tri-State ) - Most people associate blackouts with air conditioning being run in the summer, but thousands of people in the Tri-State have been dealing with blackouts in subzero cold since Sunday night.

It started when trees took down some lines near Loveland. Much of that area was blacked out all day Monday as temperatures plummeted. A pair of warming centers were set up, and by late Monday afternoon, electricity had been restored.

Monday evening, Duke Energy workers were called out again to multiple problems that blacked out about 8,000 customers in various parts of the Tri-State. The biggest issue was around Middletown where nearly 7,000 homes and businesses lost electricity because of problems with transmission lines. Another thousand lost power around Bethel, and there were other scattered issues for several hundred people in Sharonville, Cold Spring, and Ludlow.

Furnaces and space heaters running at night have been putting a larger-than-usual strain on the electric grid. Duke Energy has extra workers in the area to deal with all the problems, but the utility says people should be patient and have a cold weather plan in case they lose power. 

A spokesperson for Duke Energy says their grid is working fine, but they still recommend people ease up on power consumption.  Sally Thelen says they don't want customers to get a shock when they open up the power bill in February.  Thelen says lowering the temperature in your house by just a few degrees can save a lot of money.