Weather guides

Official weather categories carry precise meanings and casual sounding names. These pages explain what each one actually means, in plain language, and link to the live tool that shows it.

• What a Slight Risk actually meansThe Storm Prediction Center's five severe weather risk categories, in plain language, and what each one should change about your day.
• What the colors on a weather radar meanGreen, yellow, red and purple on a weather radar, what they actually measure, and the one thing radar colour cannot tell you.
• Watch or warning: the difference, and why it mattersA watch means be ready. A warning means act now. The plain difference between the two, plus where advisories fit.
• Heat Advisory or Extreme Heat Warning: what each one meansHow the National Weather Service escalates heat products, what triggers each, and who is actually at risk.
• Is today unusual for this date?What a normal high actually is, what a record means, and how to tell whether today is genuinely remarkable or just warm.