WASHINGTON (AFP) - US weather experts Friday issued heat alerts for more than half of the 50 states as a blanket of hot air and humidity smothered the country, from Texas in the south to Maine in the northeast. "We've put out a forecast including heat alerts, advisories and excessive heat warnings for all or part of 29 states and DC, from northern Texas to Maine," National Weather Service spokesman Chris Vaccaro told AFP. The US capital could again swelter under record high temperatures of more than 100 degrees Fahrenheit (37 Celsius), and feel even hotter than Death Valley in California, he warned.