The average temperature at the start of the Boston Marathon ranges from 45-50 degrees F. The spread of temperature throughout the race can average approximately 25 degrees F, meaning the finish line temperature can average from 70-75 degrees F. However, in years past, there have been examples of extreme weather at the Boston Marathon. See below for examples:
- 1907 Traces of sleet
- 1908 Snowflakes and drizzle
- 1925 Cold wind and occasional snowflakes
- 1961 Snow squalls driven by winds of 10–12 mph; recorded temperature was 39 degrees
- 1967 Snow squalls accompanied the runners through the first five miles.
- 1970 Mix of rain and sleet; temperatures in the high 30s;
- 2007 Rain; winds gusting 25-30 mph; temperatures in the mid 40s.
Extreme Heat or Unseasonable Warmth
- 1905 The temperature was reported to have reached the 100-degree mark.
- 1909 The temperature soared to 97 degrees.
- 1915 Reports of “intense heat.”
- 1927 With the temperature reaching 84 degrees, a newly surfaced, yet uncured, road melted under the runners’ shoes.
- 1931 Reports of “terrific heat” that “spelled ruin to the hopes of countless ambitious runners.”
- 1952 The temperature rose to the upper 80s, with a high of 88 degrees.
- 1958 The temperature climbed to 84 degrees.
- 1976 For much of the first half of the race, the temperature along the course was reported to be 96 degrees.
- 1987 The temperature was in the mid/upper 80s and the humidity was more than 95 percent.
- 2004 The hottest marathon since 1976 (86 degrees at the finish) caused a record number of heat-related illnesses.
- 2012 The temperature reached 75 degrees by the start of the Women's Elite field (9:30 a.m.), with a high of 89 degrees reported in Framingham (10K mark) by mid-day.