Story has been updated to include the changes in Peoria between the two climate periods.
Peoria, Ill. (WMBD) – Have you ever looked up what the average temperature is on specific date? Perhaps you looked at average monthly and daily precipitation? If you have, you’ve taken advantage of NOAA’s U.S. Climate Normals database.
Every ten years the U.S. weather station observations are compiled, quality controlled, and used to calculate averages for a thirty year period. This latest update now gives forecasters and the public the latest averages for 1991-2020. These average provide the basis for temperature and precipitation comparisons (among other variables) to today’s observations.
Why are the U.S. Climate Normals updated?
The World Meteorological Organization (WMO) requires member states to calculate their country’s normals in ten year intervals, think of it as the Census for weather data. This data is used for national and localized averages for temperature and precipitation along with snowfall, frost and freeze days along with heating, cooling and growing degree days. This data is used so we can put today’s weather into proper context.
What’s changed since the previous update?
There’s no surprise that there’s been an upward shift in temperature averages across much of the country from the previous decade. The exception has been across the Northern Plains where there’s been some slight cooling. When it comes to precipitation many locations east of the Rocky Mountains have seen an increase in precipitation while the southwest has trended drier.
Here are the changes in Peoria between the two climate periods…
| 1981-2010 Climate Period | 1991-2020 Climate Period | Change | |
| Average Temperature | 51.9° | 52.7° | + 0.8° |
| Average Precipitation | 36.49″ | 37.55″ | + 1.06″ |
| Average Snow | 24.6″ | 26.2″ | + 1.6″ |
As mentioned earlier, the U.S. Climate Normals are best used for present day conditions. When it comes to looking at the impacts from climate change, it’s best to use the twentieth-century averages (1901-2000) as a benchmark which offers more consistency as conditions change over time.
