This article was originally published in 2017 but has been updated to include relevant content and additional information.
A cold front is a boundary of air that brings cooler temperatures, a drop in air pressure, and a change in wind direction. Clear and sunny skies ahead of the cold front are quickly replaced by clouds, precipitation, and cooler temperatures that develop along and behind the cold front. Conversely, during a warm front, clouds and precipitation form ahead of the warm front and bring an increase in temperature and clear skies.
How Does a Cold Front Form?
Cold fronts are usually on the back side of a low pressure system, generally extending to the west or south from the center of the low pressure system, as the back side of the system is usually pulling cold air in from the north. On weather maps, they are defined as blue triangles that point in the direction that the front is moving.
When Does Rain Occur in a Cold Front?
Rain occurs along and behind the cold front. Since cold air is more dense and heavier than warm air, the cold air wedges itself under the warm air, causing the warm air to rise. This rapid process is called frontal lifting and allows for precipitation to develop along and behind the frontal boundary.
Can I Measure a Cold Front?
The AcuRite Atlas™ and AcuRite Iris™ wireless weather stations can measure the passage of frontal boundaries right at your home! By observing rapid temperature drops combined with drastic wind shifts, your home weather station can detect cold fronts! You can also watch for the precipitation that falls behind the cold front, because monitoring rainfall is important for our home and garden!
Cold vs. Warm Fronts
Cold fronts and warm fronts are both defined by a sudden change in temperature and a drastic change in wind direction. The difference between these two types of fronts is where the precipitation occurs. Precipitation develops along and behind cold fronts, whereas it develops ahead of warm fronts — important to remember when wanting to measure rainfall!