Boston attracts throngs of visitors year-round. Between April and November, there are hardly any slow times. Make reservations as early as possible if you plan to visit during traditionally busy periods.
The periods around college graduation (May and early June) and major citywide events are especially busy. Spring and fall are popular times for conventions. Families pour into the area in July and August, creating long lines at many attractions. Summer isn't the most expensive time to visit, though: Foliage season, from mid-September to early November, when many leaf-peepers stay in the Boston area or pass through on the way to other New England destinations, is a huge draw. December is less busy but still a convention time -- look out for weekend bargains.
The "slow" season is January through March, when many hotels offer great deals, especially on weekends. However, this is when unpredictable weather plagues the Northeast (often affecting travel schedules) and when some suburban attractions close for the winter.
Weather
You've probably heard the saying about New England weather: "If you don't like it, wait 10 minutes." Variations from day to day (if not minute to minute) can be enormous. You can roast in March and freeze in June, shiver in July and sweat in November. Dressing in layers is always a good idea.
Spring and fall are the best bets for moderate temperatures, but spring (also known as mud season) is brief. It doesn't usually settle in until early May, and snow sometimes falls in April. Summers are hot, especially in July and August, and can be uncomfortably humid. Fall is when you're most likely to catch a comfortable run of dry, sunny days and cool nights. Winters are cold and usually snowy -- bring a warm coat and sturdy boots.
Poetry 101 (Degrees) -- In Boston, you can check the weather forecast by looking up at the short column of lights on top of the old John Hancock building in the Back Bay. (The new Hancock building is the 60-story glass tower next door.) It has its own poem: Steady blue, clear view; flashing blue, clouds due; steady red, rain ahead; flashing red, snow instead. During the summer, flashing red means that the Red Sox game is canceled.
