A mass of frigid air is moving over Arkansas, and a hard freeze is forecast for much of the state tonight. The overnight freezes are expected to last through at least Thursday. The National Weather Service says the weather will be the coldest so far this fall. Lows tonight are to be in the teens and mid 20s. Highs tomorrow will be only in the 30s to the mid-40s. Temperatures are to fall more overnight tomorrow, with Wednesday morning lows in the low teens in north Arkansas and in the low 20s near the Louisiana border. No precipitation is forecast.