Boston Weather In March
Boston March Weather is about 10 degrees warmer by the end of the month than it is in the beginning of the month, and it is approximately 50°F. If you are visiting in the beginning of the month you should definitely plan on seeing winter weather, and its not out of the question that it could be cold at any time in Boston in March.
Golf is a possibility on a really nice day towards the end of the month. The weather can be great at times for walking or running, just look at the forecast to see if you are better off walking or running later in the day or if it will be warm enough for you earlier in the day. Hourly weather forecasts can be very helpful.