Flooding

Street Flooding

Flooding Hazards


A flood is a general and temporary condition where two or more acres of normally dry land or two or more properties are inundated by water or mudflow. Flooding in McKinney can result from hurricane remnants, dam / levee failure, clogged drainage systems or rapid accumulation of rainfall.

Flash Flood vs. Flood
What’s the difference between a flash flood and a flood? Flash flooding occurs during heavy rain events and happens very quickly. It ends quickly as well. Flooding occurs as the result of a more prolonged rain event or lake / creek overflow. It’s more gradual, more predictable and lasts longer. Dam / levee failure may result in flash flooding and flooding.
Flood risks are categorized as high-risk areas (Special Flood Hazard Area), moderate-to-low risk areas (Non-Special Flood Hazard Area) and undetermined-risk areas. Flood maps, known as Flood Insurance Rate Maps (FIRMs) have been created to display these risks. The National Flood Insurance Program was created in 1968 by Congress to help provide a means for individuals to protect themselves financially, since most homeowner's insurance does not cover flooding.

To see what areas in McKinney are at risk, please view our flood plain map, provided in conjunction with the Geographic Information Systems department.

Watch Versus Warning


  • Flood Watch: Issued when flooding is possible in a given area.
  • Flash Flood Watch: Issued when heavy rains and flash flooding are possible. You should be ready to move to higher ground immediately.
  • Flood Warning: Issued when flooding is occurring or is imminent. If you are advised to evacuate, do so immediately.
  • Flash Flood Warning: Issued when a flash flood is occurring and moving to higher ground is necessary.