Arizona experienced its hottest start to summer on record during June through August 2023, the National Weather Service in Phoenix said, citing temperature records dating back to 1895. The daily average temperature reached 97°F, surpassing the previous record set in 2020, reflecting a long-term warming trend in the state.
Meteorologist Matt Salerno with NWS Phoenix said the period marked the hottest three-month stretch since record-keeping began in 1895, including the hottest July and the second-hottest August on record. The start of June 2023 was also among the hottest early summers recorded in the city, with a 31-day streak of highs at or above 110°F (43.3°C) in July, surpassing the previous record of 18 consecutive days set in 1974, Salerno added.
The National Weather Service (NWS) in Phoenix reported that the daily average temperature for June through August 2023 reached 97°F (36.1°C), breaking the previous record of 96.7°F (35.9°C) set in 2020.
Phoenix’s 2023 summer heat was part of a broader regional heat wave affecting Texas, New Mexico, Arizona, and California’s desert areas, the NWS said. By early September 2023, Phoenix had recorded 55 days with temperatures at or above 110°F, emphasizing the persistence of extreme heat throughout the season. Excessive heat warnings were frequently issued, with forecast highs regularly exceeding 110°F during the summer months.
Tucson also tied its hottest summer on record, according to the NWS. The city’s average daily temperature for June through August 2023 was 90°F, placing four of the last five summers among Tucson’s five hottest since records began in 1895. Tucson’s average high temperature reached 103.4°F, which was 3.4°F above normal and just 1.3°F cooler than the city’s hottest summer in 1994. The average low temperature hit a record 76.6°F, 2.4°F above normal, reflecting warmer nighttime conditions. Tucson experienced 78 days with temperatures of at least 100°F, 23 days more than usual, including 38 days at or above 105°F and six days at or above 110°F. The city also recorded 67 nights with lows remaining above 75°F and 21 nights at or above 80°F, setting records for persistently hot overnight temperatures.
Nighttime heat was a significant factor in the overall temperature records. Phoenix set a record for the warmest daily low temperature at 97°F (36°C) on July 19, 2023, highlighting the intensity of overnight heat. Meteorologists and climatologists note that elevated nighttime temperatures reduce relief from daytime heat and are key indicators of intensifying summer heat in Arizona’s urban areas.
Long-term data show a clear warming trend in Arizona. Climatologist Erinanne Saffell said the state’s average temperature has risen about 2.5°F since records began in 1895. Historical records maintained by the NWS and analyzed by Arizona State University (ASU) confirm that recent decades include many of the hottest summers on record. ASU’s analysis described the 2023 season as a record-breaking summer in Arizona, tying local temperature extremes directly to the statewide historical period starting in 1895.
In Phoenix, the summer of 2020 previously held records for the hottest summer, with an average maximum temperature of 107.9°F and an average temperature of 96°F. That year also saw the highest number of days reaching 110°F, with 35 such days recorded by August. The average minimum temperature in 2020 was 84.2°F, tying a record set in 2006. These records were surpassed or closely matched during the 2023 summer, underscoring the trend toward more frequent and intense heat events.
The extreme heat in Arizona fits within a broader national and global context. A Stacker analysis of NOAA data identified July 2022 as the third-hottest July in the continental United States since 1895, with multiple states, including Arizona, experiencing some of their hottest months on record. The World Meteorological Organization reported August 2023 as the hottest August ever recorded worldwide, coinciding with Phoenix’s record-breaking summer temperatures.
Arizona’s official statewide temperature record, which begins in 1895, serves as the baseline for assessing these long-term trends. Climatologists and meteorologists use this historical data to contextualize current heat extremes as part of a multi-decadal warming trajectory. The record-setting temperatures in 2023 and recent years reflect this ongoing trend documented by the National Weather Service, Arizona State University, and state climatologists.
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