Tens of thousands of Texans were without power Tuesday morning, but the statewide electric grid wasn’t to blame. With the current cold snap’s most frigid temperatures still to come, electricity demand already has had its biggest spike since last January.

Snow, sleet and freezing rain across Central and South Texas could bring down power lines, causing localized outages beginning Monday evening.

Another Arctic blast of freezing temperatures will test the ERCOT grid during this Martin Luther King Jr. holiday weekend and early next week. According to the National Weather Service, a disturbance moving in Monday to Tuesday could bring light snow to North Texas,