The autumnal equinox arrives at 10:29 this evening, bringing astronomical summer to an end. But despite the arrival of fall, temperatures are going to be on the rise this week. The highs for today and tomorrow will only reach the upper 60s to lower 70s as high pressure builds in from the west. Tonight's low may dip into the lower 50s, even in Manhattan, making it the coolest night since late-May.
That high pressure system covers the country east of the Rockies, so we can expect clear skies and slowly rising temperatures all week long. Wednesday and Thursday should warm to the lower to mid 70s and we could be in to the upper 70s by Friday. The warmest weather is coming week should be on Saturday when we could hit the lower 80s in the city.
The forecast models are hinting at a weak low pressure system moving up the coast on Thursday, but the massive high pressure system we are under should keep any precipitation well to our east. The lack of rain is starting to be a concern as abnormally dry conditions now stretch from northeastern Pennsylvania to eastern Massachusetts. August and September rainfall over the city's water supply upstate has been less than half of normal, but thanks to a wet July the reservoirs are currently slightly above average.