Boston Marathon weather leans cool

Boston Marathon runners are heading toward a cooler race day on Monday, April 20, with early forecasts pointing to dry conditions and temperatures below the usual mid-April range in Boston. (bostonglobe.com) The 130th Boston Marathon is scheduled for Patriots’ Day, April 20, and the Boston Athletic Association says 30,000 participants will race from Hopkinton to Boylston Street. The field includes runners from more than 130 countries and all 50 states. (baa.org, boston.com) Boston Athletic Association organizers have shifted to six start waves this year, up from four in prior years. Official buses for Wave 1 begin loading at 6:45 a.m., and the last bus to the start leaves at 9:30 a.m. (boston.com, baa.org) For marathoners, cooler air usually means lower heat stress over 26.2 miles, especially on a course that starts in Hopkinton and does not finish until late morning or afternoon for many runners. Boston’s route also exposes runners to changing conditions across eight cities and towns before the finish in Copley Square. (boston.com, wgbh.org) The long-range comparison is what makes this forecast notable. WCVB says April 20 in Boston averages a high of 58 degrees and a low of 43 degrees, while current outlooks described by local forecasters have trended several degrees cooler than that. (wcvb.com, bostonglobe.com) Boston Marathon weather has swung wildly over the years, from snowflakes in 1907, 1908, 1925, 1961, and 1967 to soaking rain in 1970, 2007, 2015, and 2018. WCVB also notes extreme heat years including 1905, when temperatures reached 100 degrees, and 1976, when much of the course reached 96 degrees. (wcvb.com) GBH reported that the 2011 race brought temperatures in the 40s and 50s plus a strong tailwind, helping produce Geoffrey Mutai’s 2:03:02 course record. A year later, the 2012 race started in the 60s and climbed into the mid- to upper-80s, pushing organizers to urge runners to slow down or defer. (wgbh.org) That history is why a cool, dry setup gets attention a week out. In Boston, “Marathon Monday” can mean anything from snow squalls to heat warnings, but this year’s early signal is for a race that may be kinder to runners than many feared. (wgbh.org, bostonglobe.com)