The new weather normal in the US: Hotter than it used to be, thanks to climate change

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  • Climate normals are 30-year averages of climatological variables such as temperature and precipitation.
  • “Almost every place in the U.S. has warmed from the 1981 to 2010 normal to the 1991 to 2020 normal.”
  • The USA’s normal is not just hotter, but also wetter in the eastern and central parts of the nation.

The United States’ weather “normals” have gotten warmer: What was considered “normal” weather a couple of decades ago is about a degree (Fahrenheit) warmer now, scientists announced Tuesday. 

Scientists have long referred to our wild extremes in weather, including warmer temperatures and changes in rainfall patterns due in part to human-caused climate change, as being the new normal, and now we have hard data on that saying.

Every 10 years, the National Oceanic and Atmospheric Administration (NOAA) releases an analysis of U.S. weather of the past three decades that calculates average values for temperature and rainfall.

These climate normals are 30-year averages of climatological variables such as temperature and precipitation, which give us a reference point for comparing current weather against what’s considered “normal.” They are calculated using climate observations collected at local weather stations across the country, NOAA  said.

These “normals” also provide important information for a range of economic sectors, informing growers’ decisions on when to plant crops and what crops to plant, how electrical utilities can expect energy demand to vary by season, and planning construction projects, according to the non-profit group Climate Central. 

Warming between our new normals period (1991-2020) and the previous one (1981-2010) was widespread across the U.S., with the exception of the northern Great Plains, which cooled slightly.

“Almost every place in the U.S. has warmed from the 1981 to 2010 normal to the 1991 to 2020 normal,” said Michael Palecki, NOAA’s normals project manager.

Dating back several decades, with each decadal update of the climate normals, temperatures keep creeping up, Climate Central said. 

New normals are warmer because the burning of fossil fuels is making the last decade “a much hotter time period for much of the globe than the decades” before, said Cornell University climate scientist Natalie Mahowald.

The USA’s normal is not just hotter, but also wetter in the eastern and central parts of the nation and considerably drier in the West than just a decade earlier.

According to NOAA, at least some of that wetness in the central and eastern U.S. is linked to the overall climate warming and “wetting” of the atmosphere that’s occurred as rising temperatures cause more water to evaporate from the ocean and land surface.

However, precipitation – regardless of human-caused climate change – varies a lot from place to place across the United States, NOAA said.

As noted by the Capital Weather Gang, there are signs that a multi-decade megadrought may have already set in over the southwest U.S. 

Contributing: The Associated Press