Heatwave and high humidity to blast much of US: ‘impactful to anyone’

People play in the fountains by the East River during a heat advisory in Brooklyn, New York, on 19 May. Photograph: Adam Gray/AP View image in fullscreen People play in the fountains by the East River during a heat advisory in Brooklyn, New York, on 19 May. Photograph: Adam Gray/AP Heatwave and high humidity to blast much of US: ‘impactful to anyone’ Forecasters expect days of high temperatures in central and eastern US before Fourth of July and World Cup festivities A long and dangerous heatwave will blast a large swath of the central and eastern United States for the upcoming week, the National Weather Service (NWS) said on Sunday – with temperatures rising ahead of the Fourth of July holiday and feeling even hotter because of high humidity also arriving. Already parts of the US, especially Phoenix and central Texas, and much of the south-west were experiencing temperatures of about 100F (38C) on Sunday, while the NWS warned of severe wildfire conditions developing across much of the west as new fires popped up across the region. On Sunday, more than 130 million Americans across southern and Great Plains states were under moderate to severe heat risk conditions, according to NWS maps, with that area forecast to expand and temperatures to intensify as the week drags on. Forecasters say several days of high temperatures – some above 100F – will settle in across the lower Great Lakes, the mid-Atlantic and the Mississippi and Ohio River valleys. Some record highs could be set in areas from the lower Great Lakes to the mid-Atlantic and New England later in the week, NWS meteorologist Bryan Putnam said. Four people have died from flash floods in Kentucky, governor says Read more A number of big cities could see their highest temperatures of the year so far as they host World Cup matches and celebrations for the US’s 250th anniversary . Feeling the heat will be the east coast cities of New York City, Philadelphia, Washington and Baltimore, and midwestern and Great Lakes cities including Chicago, Indianapolis, St Louis and Detroit. Southern cities such as Dallas; Little Rock, Arkansas; and Memphis, Tennessee, will also see high temperatures. High heat will last into next weekend across the Great Plains, the south-east and the mid-Atlantic, the NWS said. Temperatures will reach well into the 90s and low 100sF, the NWS said. High humidity will lead to heat indexes of 100-110F, and as high as 115F. “That’s heat that’s impactful to anyone,” Putnam said. “It’s not just older adults or younger children or people who are spending a ton of time outdoors, maybe straining themselves a little more than normal. This is heat that really could impact everyone, especially with people outdoors going into the holiday weekend.” The heat index, which factors in humidity and is included on many weather forecasts, provides a sense of how hot it really feels – and what’s dangerous for prolonged exposure or strenuous activity. View image in fullscreen People are seen at the