The weeks when hawks are likely to migrate through Massachusetts are fairly predictable. The specific days when you are most likely to see them are less predictable, and more weather dependent. The best migration conditions occur the day of and up to two days after the arrival of a high-pressure system or cold front. The reason for this is that thermals, or columns of warm air that rise through cooler air high above the ground, tend to occur when the cold clear air that a cold front brings flows over the warm earth on a sunny day. Hawks, particularly broad-winged hawks, take advantage of these thermals, riding them higher and higher in wide circles until the thermal dissipates, at which point the hawks peel off and glide in the direction of their migration.
Winds play a large part in hawk migration activity.
Virtually any open site with a good view of the north or northeast horizon will afford you a good view of hawks in the fall. However, there are two locations in Massachusetts which are considered premium hawk-watching sites. Mount Tom, located in Easthampton, near the center of the state, is a popular destination for serious hawk watchers. In the fall it is considered to be one of the most consistently productive sites in New England. Closer to home is Wachusett Mountain in Princeton.