Temperatures are often warmer in the southern part of the state with its close proximity to the Gulf of Mexico , while the northern parts of the state , mostly in the Appalachian Mountains in the northeast , tend to be slightly cooler . Temperatures tend to be warmer in the southern part of the state with its proximity to the Gulf of Mexico , while the northern parts of the state , especially in the Appalachian Mountains in the northeast , tend to be slightly cooler .