Science and TechClimate Change


Monday was officially the hottest summer day ever

No, it's not your imagination. This truly has been the hottest summer ever. Experts predict future summers could be even hotter.
A digital billboard displays an unofficial temperature, Monday, July 17, 2023, in downtown Phoenix.
Posted at 8:40 AM, Jul 18, 2023

Summer has not peaked yet, but 2023 will likely go down as the hottest season ever recorded in the Northern Hemisphere. 

According to National Oceanic and Atmospheric Administration data, air temperatures in the Northern Hemisphere reached an average temperature of 72.2 degrees Fahrenheit, making it the hottest day on record for the hemisphere. The record comes just weeks after the world as a wholeset new heat records several days in a row.

The temperature was 1.92 degrees above the average temperature set between 1979 and 2000. 

There are also indications that this summer could bring the warmest sea surface temperatures on record. As of Monday, the average sea surface temperature in the Northern Hemisphere was 75.74 degrees Fahrenheit. 

Sea surface temperatures are more than 2 degrees warmer than average for this time of year, according to the NOAA data. 

Generally, sea surface temperatures are at their warmest in late August and early September. 

Earlier this year, global sea surface temperatures set a record in nearly 40 years of monitoring. It was measured at 69.98 degrees Fahrenheit in early April. 

A man walks along a sidewalk under misters in Arizona.

Sidewalk, contact burns a real concern with extreme heat

With temperatures expected to topple 120 in the Southwestern U.S., officials are warning that sidewalks and other surfaces are too dangerous to touch.


Experts say the combination of climate change and a subsiding La Niña pattern is contributing to the record warmth. 

The rise in sea surface temperatures can be directly attributed to higher levels of greenhouse gas, NOAA senior scientist Michael McPhaden previously told Scripps News. Greenhouse gases come from the burning of fossil fuels like gasoline for cars or coal for electricity. 

"The fact is we have the data and we have the physical understanding of how the climate system works, that this correlation, that this connection between rising greenhouse gases and rising global temperatures is real," McPhaden said. 

The heat was not expected to subside for many Americans. Heat advisories and extreme heat warnings extend from California all the way to Florida. 

The high temperature is expected to reach 117 in Phoenix on Tuesday, which would set the daily record, according to the National Weather Service.

Although not expected to hit a record, Las Vegas will still be incredibly warm with a projected high temperature of 112.