The passage of a Canadian cold front will introduce a touch of Autumn to the northeastern US. Cool and breezy weather conditions will prevail as the heat and humidity is replaced by this polar air.

An advancing cold front from the north is combining with a polar high pressure system and will bring on the first frost and freeze of the season for a large part of the Northeast. A freeze advisory is already in effect from northern Pennsylvania to Upstate New York and Northern New England. Some records are likely to be broken as some locations will be getting unseasonably cold.

The combination of the cold air, calm winds and clear skies will allow temperatures to plunge to freezing point and below. After 3 weeks of intense tropical activity the weather has settled down over large parts of the US and northern Europe. Even Britain, which has had a succession of depressions crossing for a large part of the summer, is now enjoying the calming influence of a giant Scandinavian high.

A frost is not unusual at this time of year, but a widespread frost like this one is a little too early as Autumn doesn't officially arrive until after the Autumn equinox on the 22nd September this year.
In some parts of the the north east this freeze is arriving up to a month early.

The cold air that moved into the East erased the midsummer heat and humidity that spread across the East on Sunday.

But should we be surprised in these times of global warming that a freeze has hit so early? No, of course not, random fluctuations are all part of the unpredictability of the world's climate, and also we are still experiencing La Nina in the Pacific which could, perhaps, explain some of the cooler global temperatures we have seen this year.

La Nina is the meteorological opposite cousin of the better known El Nino. During a La Nina episode the central and eastern pacific ocean cools extensively. La Nina begins with a build up of colder than normal water below the surface of the central pacific. The easterly trade winds and wave action will pull this colder water to the surface off the western coast of northern South America, around Peru and Ecuador.

La Nina tends to be a much less damaging event than El Nino, but globally will increase whatever weather patterns may be established. For instance the number and intensity of atlantic hurricanes may increase, those areas of the world that experience drought are likely to have a particularly harsh drought . Drier areas will be drier, and wetter areas will be wetter.

Also this points to colder areas being colder. And this is born out by the recent discovery that the Arctic summer ice sheet is slightly larger than it was 12 months ago. And of course this directs us back to the early freeze in the north eastern US states.

So are we surprised by this early freeze? Nope, of course not, these days the weather very rarely is truly surprising.