An unusually wide-reaching and long-lasting heat wave has gripped at least six states for an entire week, breaking or tying dozens of hot weather records. Temperatures were so high that certain aircraft couldn't fly out of airports including Phoenix and Palm Springs, offering a preview of what may happen to transportation networks as the climate continues to warm due to human-caused climate change.
Here are 7 of the most impressive heat records set so far.
1. Tucson's 115-degree streak
Tucson, Arizona, set its longest-ever streak of 115-degree or higher days, with a high temperature of 115 degrees Fahrenheit on June 19, 120 degrees on June 20, and 115 degrees on the 21st.
Before 2016, the desert city had only reached 115 degrees four times in its entire history.
According to the National Weather Service (NWS), there have now been more than 200 hot weather records set or tied in this decade. This means it's all but assured that the 2010s will go down in history as having the greatest number of hot weather records in the state since the 1970s.
Climate data shows that since 1951 to 1980, the average number of 100-degree or higher days in Tucson has increased from 40 to 62 days. Projections show this number may increase to around 100 days by 2100.
In addition to the daytime high temperatures in Tucson, overnight lows also set records: The low temperature on Tuesday morning only fell to 86 degrees Fahrenheit, which was the highest June minimum temperature on record there.
2. Historic California and Nevada heat
On June 20, Palm Springs, California, tied its record for the fifth-warmest day since records began there in 1893. The temperature reached a searing 122 degrees Fahrenheit. On the same day, the appropriately named Thermal, California, saw its 2nd-warmest high temperature: 123 degrees.
In Needles, California, the temperature climbed even higher, to 125 degrees, also on June 20. This tied the all-time hottest temperature on record there, which was set on the same day last year.
Last Vegas also tied its all-time highest temperature record of 117 degrees Fahrenheit on June 20.
3. Phoenix on fire
On Tuesday, the temperature in Phoenix hit 119 degrees Fahrenheit, the fourth-highest temperature on record there. Out of 11,060 days since summer records began in Phoenix in 1896, the city has only seen 16 days with a high temperature of 118 degrees Fahrenheit or higher, including Tuesday. Notably, all but one of these days have been since 1989, according to the NWS.
The three straight days of 117-degree or higher temperatures in Phoenix during this heat event was the 2nd-longest stretch on record there, ending just shy of the all-time record of four such days in June 1990.
Yuma, Arizona, also recorded its fourth-highest temperature on record, at 120 degrees Fahrenheit, a level Yuma also reached in June of last year.
4. Heat went big and didn't go home
The heat wave has been sliding northwest with time, eventually causing near record-breaking temperatures in the Pacific Northwest this weekend.
During the peak of the Southwest heat wave, however, the extent of the dangerously warm temperatures was unusual. This map from the NWS shows all the locations across parts of the Southwest that recorded high temperatures of at least 100 degrees Fahrenheit on June 21.
5. Grounded planes
Since June 18 more than 100 flights were canceled due to the heat, according to American Airlines and news reports. It's possible that even more flights were affected if other airlines are taken into account, but American is the main operator at Phoenix's Sky Harbor International Airport, where temperatures exceeded safe operating limits of some aircraft types.
The canceled flights were all operated by regional jets, including Canadair Regional Jets.
Because hotter air is thinner, punishing heat waves make it harder for aircraft to generate the lift they need to become airborne. This requires the use of longer runways, and some planes aren't certified to fly in ultra-hot weather.