Enjoy the pleasant, cool weather while it lasts, as the return to scorching temperatures is just around the corner. Low dew point air will persist for the next 48 hours on the eastern flank of a high pressure ridge. Northerly winds are ushering in September like temperature and humidity values for the time being. However, the ground is getting drier with each passing day. Dry begets dry; heat begets dry. They feedback on each other to promote an increasingly hot picture for our area. Heat waves will gradually become longer and stronger overall, and this upcoming heat surge will certainly be more impressive than the last for much of the Northeast. NYC finished with a +3.4 temp departure for the month of June, coming in 4th warmest on record. Many locations recorded over 10-12 90 degree days already, and it's not even the 4th of July. 
Note the 12z ECMWF forecast valid Monday, July 5th. 850mb temperatures exceeding +20c within that red circle over the Ohio valley and Mid atlantic. With a NWLY downsloping flow, drying ground, strong sun, and >+20c 850mb temps with a 588-594dm upper ridge near the region, we're talking ambient air temperatures of 95-100 degrees on average. The heat actually becomes more intense by Tuesday and Wednesday (if you can believe it) with increasing dew points, which will add to the oppressive feel of this airmass. Temepratures are liable to break the century mark in Newark, NJ for three consecutive days, probably Mon-Wed. Other normally warm spots will also hit 100F or maybe slightly higher on those days. So nevermind heat wave criteria (3 days in a row with 90+ temps); this will be an extreme, dangerous situation with 97-102 degree highs. The coolest coastal areas will be at or above 90 as well, so little relief to be found across the NYC metro area.
Looking into the future, the hot summer that was talked about in the summer outlook will continue. We may have temporary cool spells, but overall, expect hot/humid Bermuda high pressure dominated regime to persist for the next few weeks.
Enjoy the holiday weekend and remember to limit your time outdoors in the extreme heat next week. Highs will approach the century mark for three, potentially even four days. Remember to keep hydrated and exercise only in the early mornings or late evenings if any indoor facility is not available. Air quality will also be very poor, and may be a health hazard for sensitive groups. This heat wave will go into the record books, similar to many spells we had in 1988, 1995, 1999, and 2005.
https://nymetrowx.blogspot.com/2010/07/independence-day-to-ring-in-record.html?showComment=1278030153779#c1583201893845343098'> July 1, 2010 at 8:22 PM
Do you guys think that temperatures will be warmer near PHL? I noticed the ECMWF and GFS have warmer H85 temps there, specifically on Wednesday of next week.