![\"Declaration](\"https:\/\/www.newsbeep.com\/us-pa\/wp-content\/uploads\/2026\/07\/1783175831_394_0x0.jpg\")
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The signing of the Declaration of Independence in Philadelphia on July 4th, 1776 (by John Trumbull, American, 1756 – 1843), 1819. The painting shows the five-man drafting committee presenting the Declaration of Independence to the United States Congress, and is located in the Capitol rotunda. Oil on canvas. (Photo by GraphicaArtis\/Getty Images)<\/p>\n
Getty Images<\/p>\n
Philadelphia, Pennsylvania is likely to experience one of the warmest 4th of July celebrations in the era of official records. A massive heat dome has gripped much of the eastern United States this week. While July 4th represents the near peak of the current heatwave, there are a few days left of dangerous heat. As our country celebrates the Semiquincentennial, which is the 250th anniversary of the United States Declaration of Independence, I thought it would be fun and instructive to compare weather conditions on that date in 1776 and today. And by the way, I am able to do this thanks to Thomas Jefferson.<\/p>\n
July 4th, 2026<\/p>\n
On the eve of July 4th, organizers canceled <\/a>Philadelphia\u2019s Salute to Independence Semiquincentennial Parade because of temperatures in excess of 100 degrees Fahrenheit. The previous day Philadelphia tied a maximum temperature record with a reading of 103 degrees Fahrenheit. The Great American State Fair in Washington D.C. was temporarily disrupted<\/a> by extreme heat on Friday, and the district\u2019s July 4th Independence Day parade was also canceled. <\/p>\n Expected temperatures from Washington D.C, to Boston, Massachusetts on the afternoon of July 4, 2026.<\/p>\n NOAA and Tropical Tidbits<\/p>\n The National Weather Service has issued an extreme heat warning<\/a> for the Philadelphia area until 8 pm on July 4. \u201cDangerously hot conditions with maximum heat index values between 105 and 110 degrees expected,\u201d wrote the NWS. \u201cHeat related illnesses increase significantly during extreme heat and high humidity events,\u201d they continued. While we are all susceptible to adverse effects from heat, which kills more Americans annually than any other weather event according to NWS, some groups are particularly vulnerable. These include elderly, the poor, children under 5, and communities of color. <\/p>\n Weather-related heat fatalties in the U.S.<\/p>\n NWS<\/p>\n While the triple digit readings in the daytime garner headlines, elevated temperatures at night are also very dangerous. \u201cVery warm low temperatures in the mid 70s to low 80s at night will not offer any relief from the heat,\u201d cautioned the NWS Philadelphia. They also warned that, \u201cMultiple days of near record breaking temperatures will exacerbate the impacts from the heat and humidity.\u201d There is also a 30% chance of afternoon thunderstorms in the late afternoon. That rainfall could certainly provide some temporary relief.<\/p>\n July 4th, 1776<\/p>\n What was the weather like on this date 250 years ago? In 1776, we did not have the National Weather Service. That didn\u2019t come along until 1870. However, there is information about the weather on that date available thanks to Thomas Jefferson. It is well known that Jefferson kept meticulous weather records over several decades. \u201cOn July 4, 1776, Thomas Jefferson awoke to a cool Philadelphia summer morning: it was 20\u00b0C (68\u00b0F) at 6 am,\u201d according to the American Museum of Natural History website.<\/a> By 1 pm, temperatures were in the mid-seventies, according to a post by the organization Climate Reality.<\/p>\n And Not Or<\/p>\n I gave you a glimpse of \u201cweather\u201d on two dates in history. It is irresponsible to draw conclusions from two data points, but I don\u2019t have too. Using proxies for past weather and more recent observations, studies confirm that climate is warming. I encourage you to read the most recent U.S. National Climate Assessment report<\/a> housed at Climate.us. \u201cSince 1970, July has warmed in 94% of 243 U.S. cities analyzed \u2014 by 2.6\u00b0F on average,\u201d according to a report<\/a> by Climate Central. In most places, July is the hottest month of the year.<\/p>\n July temperature trends in Philadelphia.<\/p>\n Climate Central<\/p>\n Since 1970, temperatures have steadily increased. The graphic above shows that there is year-to-year variability due to things like El Ni\u00f1o and La Ni\u00f1a, but the overall trend clearly establishes a warming trend. By the way, El Ni\u00f1o years, which we are currently within, tend to be warmer. <\/p>\n At this point, I will pause and reaffirm that scientists like me understand that climate has changed naturally throughout history. I promise you we know about icehouse periods, hothouse periods, Younger Dryas, the 1930\u2019s Dust Bowl and so forth. Since the Industrial Revolution, a human steroid is sitting on top of the naturally-varying climate. It is a flawed narrative to assume it is either natural \u201cor\u201d anthropogenic change. Like most things in life, \u201cand\u201d is more appropriate. <\/p>\n Graphic showing global carbon dioxide emissions (blue) and global temperature change anomalies.<\/p>\n Climate Central<\/p>\n","protected":false},"excerpt":{"rendered":"The signing of the Declaration of Independence in Philadelphia on July 4th, 1776 (by John Trumbull, American, 1756…\n","protected":false},"author":2,"featured_media":235462,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[5781,20960,100208,3687,69,71,70,9880,49232,1133],"class_list":["post-235461","post","type-post","status-publish","format-standard","has-post-thumbnail","category-philadelphia","tag-climate","tag-declaration-of-independence","tag-heat-dome","tag-national-weather-service","tag-philadelphia","tag-philadelphia-headlines","tag-philadelphia-news","tag-semiquincentennial","tag-thomas-jefferson","tag-weather"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/posts\/235461","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/comments?post=235461"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/posts\/235461\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/media\/235462"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/media?parent=235461"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/categories?post=235461"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/tags?post=235461"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}