Weather 101: Understanding Climate Normals

“Today’s high temperature was 85 degrees, that’s 5 degrees warmer than normal.”

You’ve probably heard your local weather forecaster say something similar in her evening broadcast. But, how did they know what temperature is considered “normal” on that day?

NOAA’s Climate Normals offer an answer. Climate Normals are 30-year averages for climate variables like temperature and precipitation. They provide a baseline that allows us to compare a location’s current weather to the average weather that location would expect to see — whether a particular day is cooler or warmer than normal, if a particular month is wetter than normal, or if the growing season is longer than normal.

Normals are critical for characterizing current weather and climate, but they also have a wide scope of applications beyond standard weather forecasts:

  • Drought assessment. Climate Normals help assess drought conditions across the nation for the United States Drought Monitor, which is used by Federal, state, local, and tribal decision makers to trigger drought responses.
  • Freeze risk. Farmers and gardeners plan their crops, growing season, and production schedules based on local Climate Normals, which include the average first and last freeze dates.
  • Energy. For assessing energy usage, power and utility companies monitor heating and cooling degree-days and compare weather forecasts to a location’s Climate Normals.
  • Snow. Local governments use normal snowfall for winter budgetary and operations planning, including for snow plows and road salt. Knowing a location’s normal mountain snowpack is also critical for planning water resources for the warmer seasons.
  • Travel. Travelers can use a location’s Climate Normals to guide their vacation packing and planning. Travel agencies and Chambers of Commerce can look to the Climate Normals for scheduling and promotional purposes.