Temperatures this afternoon have already warmed into the low 90s across many spots and heat index values are now in the 100s.
National Weather Service forecast for the maximum heat index on Saturday.
Thursday looks to be more seasonable, with a daytime high near 87 forecast at Lehigh Valley International Airport, according to the weather service.
Washington could see its first high temperature at or above 100 degrees since 2016.
Without global action to reduce heat-trapping greenhouse-gas emissions, the number of days when the heat index - or "feels like" temperature - exceeds 100 degrees Fahrenheit would more than double from historical levels to an average of 36 across the country by midcentury and increase four-fold to an average of 54 by late century.More news: Perry hopes people 'learn' from Swift reconciliation
That break from potentially unsafe heat follows a 60% chance of rain Wednesday afternoon rising to an 80% chance Wednesday night at the airport.
An excessive heat warning remains in effect through 7 p.m. Saturday for the following counties in our area. Showers and storms are expected during the mid-afternoon hours and into the evening as the remnants of Tropical Storm Barry move through the region. "Showers and thunderstorms this afternoon and tonight will be capable of producing torrential rainfall, with local amounts of 2 to 4 inches and even higher localized amounts potentially occurring in a short period of time".
"Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors".
Know the symptoms of heat exhaustion, heat stroke and heat cramps, and what to do if you or someone you know is experiencing any of these conditions.More news: Prime Day Surpasses $4 Billion In Industrywide Sales Across 48 Hours
Storm chances will rise again during the second half of the weekend as a cold front approaches the Midwest.
"Plan to spend more time in air conditioned or well-ventilated places", the NWS advises.
Heat Stroke is a medical emergency and should be taken very seriously.
Infants, older people, women, tourists or migrants and people working or living outside are among the most vulnerable in heat waves.More news: Will Take Dog For Walk By Beach