Land-Surface Temperatures During Record Breaking Heat In Phoenix

A collection of maps developed by scientists at NASA's Jet Propulsion Laboratory depict land-surface temperatures in the Phoenix region in July 2023, during the city's record-breaking hot spell. The pictures show how a month's worth of constant daytime heating adds up, both overnight and over the course of the month.

The data were collected by an instrument on board the NOAA-NASA Suomi National Polar-orbiting Partnership (Suomi NPP) satellite, which is operated by the National Oceanic and Atmospheric Administration and NASA, during the early morning hours (around 2 a.m.) on several days in July. The pictures demonstrate how heat is retained by constructed surfaces, such as airport runways, buildings, and roadways, with temperatures occasionally remaining near 100 degrees Fahrenheit (38 degrees Celsius) for hours after sunset.

The constructed surfaces in the maps heated up more and more from July 1 to July 19, most likely as a result of the heat wave getting worse and the structures' cumulative heating. These surfaces had a high heat capacity, thus they didn't completely cool before the heat of the next day.

Phoenix's Sky Harbour International Airport, where VIIRS recorded the warmest land-surface temperature in the city, is shown in the centre of the photos. Phoenix also takes its official air temperature reading there. By such standards, July was the city's warmest month ever, with a record-breaking 31 consecutive days of temperatures above 110 degrees Fahrenheit (43.3 degrees Celsius). 18 days previously stood as the record.

Credit: NASA/JPL-Caltech