I used to think that Boston weather was notorious, until I visited enough places to know that Boston is not the only place where the weather is unpredictable. True that Southern California, Spain and Aruba all have consistently nice weather, the majority of the country has crazy weather and Boston is no exception.
As bad and unpredictable as weather can be in Boston we very rarely have dangerous weather. We have almost no tornadoes, earthquakes or dangerous floods. We do have hurricanes, but almost all houses and buildings can withstand them. It is common for trees to fall during hurricanes and this usually results in damage to buildings as well as power lines. But it is almost unheard of for anyone to be physically hurt by these events. The biggest inconvenience is usually power outages. We occasionally have big snow storms, which are annoying and can occasionally trap an elderly person or bury someone in the snow, but the numbers affected are usually very small and the biggest problem ends up being caught in traffic. Yes, we have floods but our rivers do not carry neighborhoods away. Our earthquakes are fun for scientists but almost meaningless to everyone else.
Many may disagree with me, but my opinion is that Boston has great weather. We have four complete seasons, some of which draw tourists from around the world, and enough variety to suit almost every taste (as well as to annoy almost everyone at one point or another).
Winter - Our winters begin around November and can last in bits into April. Generally the most snow comes in January and February, and the temperature can vary so much that you might just catch a 75 degree day in early November or mid April. We often have 3-4 months of snow on the ground, though it is occasionally washed away by a rain storm or unusually warm days. We used to always have white Christmas's but recently have only had them about 1/2 the time. Winter weather gets cold and windy, with temperatures occasionally dropping below zero but mostly staying in the 20s and 30s, tempered by the ocean waters nearby. People go north to ski in the winter time, though our mountains are nothing special compared with the Rockies.
Spring - Spring in Boston is really just a gradual warmup and clean up from the winter. The snows melt, the rains come, the dirty melting snow turns muddy and the leaves start to come back on the trees. The warming of temperatures are so gradual that you can have 80 degree days in March and 40 degree days in May.
Summer - At some point spring suddenly ends and it is summer. By far the biggest tourist season is the summer. Boston and New England receive visitors for several reasons:
1) Our summers are warm, but not as consistently oppressive as the south or as brutally hot as the west. It almost never hits 100 degrees and the humidity comes and goes. Summer temps range from the mid 70s to about 90. It can rain for a week or be sunny for a week, but the temperature is usually conducive to outdoor activity. When it does get particularly warm, we call it HAZY, HOT AND HUMID. This type of weather which plagues the south all summer long, comes and goes only a few times a summer, at the most.
2) We have alot to do. Whether touring the city, the suburbs, visiting the mountains or hitting the Cape or Islands, there is always something to do in summer. Many of Boston's sites can be seen all year long but the summer months are so much easier on the body and require less juggling of clothing.
3) We are a starting point for other New England vacation spots. The massive state of Maine is a summer vacation paradise for millions and sits less than 90 minutes away. Campers, boaters and hikers all go up to Maine where the air is fresh, the pine is ever present, the nights are cool and the lakes are beautiful. Bar Harbor and so many other Maine destinations are visited by millions each summer. Maine also has a large number of summer camps and family retreats. Others go to the mountains and again, many go to the Cape and Islands.
Fall - Fall means one thing to tourists in Boston and New England and that is foliage. New England foliage season is known throughout the world. Our combination of deciduous trees, rolling hills and mountains and perfect weather patterns, translate into a patchwork of color come October that is second to none. Some call it 'leaf peeping season' and it really is a beautiful time. It is also a time when the heat breaks, the summer crowds thin, and New England feels quintessentially like it should.
No matter when you visit Boston you will find weather that is manageable. It can sometimes be brutally hot and sometime be brutally cold, but it is rarely a condition that the right clothing wont prepare you for. I can remember spending time in the California desert in summer and realizing that you really have to know what you are doing or you could end up burnt, dehydrated or dead. I have spent time in Minneapolis in the winter, where you literally HAD to be in from the cold after a certain time or frostbite and hypothermia would be imminent. None of these extremes are common in Boston. If it rains you bring an umbrella, not a boat. If its cold you wear a jacket, not a space suit. If its hot, you drink extra water and put on sunblock.