The Campaign begins on Nightal 1 1372 DR, that's equivalent to December. The Winter solstice has yet to come, but the Dalelands have already seen their first dusting of snow come.
The Western Heartlands and Northern Sword Coast have been plagued by unusual weather, causing a draught in part of the Heartlands but causing terrible cold and storms near the coast. The cause of this weather is not well understood among common folk.
The return of Shade Enclave is pretty well known in adventuring circles, with many adventurers hiring out of Waterdeep, heading for the forbidden Vale of Evereska as well as other destinations.
Tilverton (Cormyr) was recently obliterated, there is conjecture that Shade was involved but it's little more than heresay in the Dalelands.
Bane's resurgence is also well known and has been a source of mixed feelings for much of the region as it has caused a schism within the Zhentarim which has thrown their organzation into chaos temporarily, however, the return of the Lord of Fear and Strife cannot be a good thing for the Realms.
Other campaign events may not be well known and players who are familiar with the events of this year should be careful not to assume what is common player knowledge is such for characters in the campaign.