This Saturday marks the 244th anniversary of Independence Day, and the day’s typical festivities—cookouts, picnics, concerts—may look quite different this year. One July 4th hallmark that is unchanging, though, is heat.
In a warming world, seemingly-small increases in average temperatures lead to big increases in extreme heat. As a result, record high temperatures have been outpacing record lows at an increasing rate. There were 49 all-time record highs across the U.S., compared with just 2 record lows over the past 12 months. This week we zoom in to look at the records set on July 4th—showing which Independence Days were the hottest, the coolest, and wettest in your area—along with July temperature trends.
Of the 242 cities analyzed, 70% (170) recorded an increase of at least 1℉ in average July temperatures since 1970, with 44% (106) registering an increase of 2℉ or more. Western cities top the list of biggest July increases, with Reno, NV warming 11.5℉ on average since 1970, followed by Boise, ID at 7.1℉.
For the rest of the summer, temperatures are expected to be hotter than normal for much of the United States, while NOAA is “virtually certain” that 2020 will be among the hottest years on record globally, with a 50% chance that it’ll take the top spot from 2016 as the hottest year in recorded history. Changing this trajectory from ever-increasing extreme heat is more pressing than ever— to sustain a habitable climate and alleviate the outsized impacts of climate change on frontline communities.
Local Independence Day climate extremes and average July temperatures from 1970-2019 were retrieved from the Applied Climate Information System for each station’s period of record. Climate Central’s local analyses include 244 stations. However, for data summaries based on linear trends, only 242 stations are included due to large data gaps in St. Johnsbury, Vt. and Wheeling, W. Va