How cold a temperature gets depends mostly on what?

Cold is the absence of heat, and thus is a product of the removal of the heat. When night falls, we experience the loss of what is called diurnal heating, or heating by the sun. This is caused by the lack of long wave radiation, radiation emitted by the sun directly on the planet, which produces heat as well as the loss of short wave radiation, energy released from the planet which was absorbed as long wave radiation.

It also depends on the season, which is caused by the angle of the Earth in relation to the sun. In the summer, the sun shines directly on the Tropic of Cancer (23 degrees 26'), causing more direct sunlight in the Northern Hemisphere to heat it up. In the winter, the sun shines on the opposite latitude known as the Tropic of Capricorn which causes less heat to generate in the Northern Hemisphere. The angle of the sun directly influences how hot and cold it becomes.

If you refer to a specific area, a city or state as opposed to the country or continent, then you need to look as what are called synoptic scale air masses and semi permanent air masses, which are bubbles of high and low pressure air that influence large regions. For example, in North America, Canada houses the Alberta High Pressure System, which commonly pushes cold air into the continental United States. As winter emerges, this air mass will move into the Central Plains. Smaller systems, known as high or low pressure systems, move throughout the world and affect local temperatures.

The parts of these systems are called the warm front, the cold front and the occlusion. The warm front is a mass of relatively warm air and the cold front is the relatively cold air. As these move over an area they will affect the temperature.

Ask your local weatherman for explanations of what systems are currently affecting your area, as they change daily.