Every 10 years, NOAA releases an analysis of U.S. weather of the past three decades that calculates average values for temperature, rainfall and other conditions. That time has come again.
Known as the U.S. Climate Normals, these 30-year averages — now spanning 1991-2020 — represent the new “normals” of our changing climate. They are calculated using climate observations collected at local weather stations across the country and are corrected for bad or missing values and any changes to the weather station over time before becoming part of the climate record.
Simply stated: The Normals are the basis for judging how daily, monthly and annual climate conditions compare to what’s normal for a specific location in today’s climate.
A few interesting things of note:
- The number of days with measurable precipitation has remained steady or decreased across Central Texas, however total annual precipitation has still increased as a result of more days with heavy rain (>1.00”). This suggests both an increased risk of drought AND an increased risk for flash flood events, a finding that is supported by scientific research.
- Annual Average Temperature has increased across all of south-central Texas, as well as the number of days with extreme warmth. While not explicitly calculated by NCEI, the annual number of 100-degree days has increased by 6 days at Austin-Bergstrom and by 11 days at Camp Mabry over the last 10 years.
- The patterns of changes between the old and new normals datasets differ somewhat from month to month and season to season.
At Austin-Camp Mabry, the average annual rainfall for the year is now 36.25 inches, which is 1.93 inches higher than the previous average. The average annual temperature is now 70 degrees, which is 0.6 degrees warmer than the previous average. The average number of days with 100-degree or higher temperatures is now 29 days.
At Austin-Bergstrom International Airport, the average annual rainfall for the year is now 35.57 inches, which is 0.93 inches higher than the previous average. The average annual temperature is now 68.4 degrees, which is 1.2 degrees warmer than the previous average. The average number days with 100-degree or higher temperatures per year is now 24.