A new heat wave is likely ahead for the Northeast through at least Tuesday, as a new ridge of high pressure briefly builds into the eastern US thanks to the westward progression of the ridge of high pressure. With a surface high pressure centered over the Southeast, that will allow for a dominant southwesterly wind and therefore above average temperature and moderate to high humidity.
Unlike past heat waves this summer, this one will be more short-lived and will feature less oppressive humidity. Nonetheless, the combination of the heat and humidity will allow for heat indices to near 100 degrees in some locations, which may make it dangerous for some.
Dew points inland will generally be in the mid 60s while at the coast it will be near 70 degrees early in the week. This translates to a sticky air mass, but not quite an oppressive one.
The heat will continue to crank in heading into Monday, with high temperatures into the 90s becoming more commonplace, especially in the I-95 corridor and near the Great Lakes. Across the interior Northeast, highs around the upper 80s will be prevalent. Skies will be partly cloudy in most areas, with the exception of a few showers and thunderstorms near the Canadian border and back into the Great Lakes associated with an incoming storm system.
Following this, a cold front will begin to approach the Northeast, allowing for temperatures to cool off to near to below average levels. Ahead of that front will be showers and storms across the interior, keeping high temperatures in the 80s. Meanwhile in the Northeast Megalopolis, temperatures will likely peak, topping off into the low to mid 90s. That will be paired with generally sunny skies, so it will definitely be a hot day in the dog days of summer.
By Wednesday, temperatures will be a bit more uncertain because it depends on when exactly the precipitation arrives to the I-95 corridor. If it happens during the latter half of the day, then many locations may have a shot at reaching 90s degrees. On the other hand, if the showers and storms move in during the morning or midday period, that will likely prevent temperatures from exceeding the mid to perhaps upper 80s. Nonetheless, it will be another warm and humid day.
It should then dry out for the end of next week thanks to the frontal passage. There may even be a more substantial round of drier air that moves in with dew points down to the 50s.