The weather 'means everything' to runners come Monday

Boston Globe

16-04-2025

Dr. Colby has led a team of atmospheric science students to collect and report real-time weather data during race day since 2012. They deliver valuable information to a couple hundred on-course personnel who man the 26 medical tents along the course route, MEMA (Massachusetts Emergency Management Association),.
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And with a course stretching 26.2 miles over hilly terrain towards the ocean can create a number of challenges depending on weather conditions. Runners might see a helpful tailwind to beat personal bests or face a strong sea breeze headwind. Hot or cold temperatures and of course, with it being spring after all, rain or snow can all come into play.
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Dehydration, heat stroke, hypothermia, and slip and falls are a few common race day health risks with weather more than not the culprit. And even the best of the best have had challenges in past years.
'2012 saw temperatures reach 86 on the course and we treated 10 percent of the field due to dehydration and exertion heat stroke cases,' said Troyanos.
'We even saw many elite runners drop out of the 2018 marathon because it was so cold,' said Chris Troyanos, retired medical coordinator of the Boston Athletic Association. 'Wind chills in the upper 30s from high winds and heavy rain led to thousands being treated for hypothermia cases — almost ten percent of the field."
This year's forecast is looking to be more favorable with partly to mostly sunny skies with temperatures likely just below or at average, reaching 55 to 60 degrees in the afternoon.
How the B.A.A. handles weather and runner safety
Troyanos has been involved with the B.A.A. and the Boston Marathon for 48 years and was the medical coordinator for the race during the last 28 before retiring after last years race — and he's seen it all.
Some 26 medical tents stretch over the length of the course and are strategically positioned so ambulances can enter and exit easily. Tents, staffed with a multi-disciplinary team of physicians, nurses, and trained volunteers stand by at the ready. Stations are positioned more back-ended along the course, starting in Ashland with a larger presence leading to the finish line.
'There are very robust treatment protocols in place for various medical situations,' said Troyanos. 'We're equipped and ready to handle surges of incidents should weather play a role in the race.'
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On high heat days, heat stroke and dehydration is treated most commonly with oral or IV electrolyte filled fluids.
With the cold, hypothermia reigns supreme. 'If wind is strong on a cold day, especially with a sea breeze near the city, it's like opening a refrigerator door,' said Troyanos. Heating units are inside the tents along with warm shelter buses nearby for folks to warm up.
Rain makes the course more slick and delivers an uptick in trips and falls that can lead to sprains and fractures.
Wet bulb globe temperature matters most
Students and faculty at UMass-Lowell's atmospheric science program are equipped with Kestrels, a handheld device that records valuable atmospheric readings such as temperature, wind, humidity, and perhaps most important — wet bulb globe temperature (WBGT).
'Students observe and report these findings every 30 minutes starting a half hour before the race and disperse the information so everyone ensuring weather safety on the course stay prepared,' said Colby.
You might be asking, what is WBGT? It's a temperature reading taking into account all of the above observations including solar radiation from the sun angle and cloud cover, assessing the heat stress on the human body — perfect for an event like running the marathon. Or simply put, WBGT tells us the effect of the atmosphere and the sun.
There are three separate thermometers used in measuring the WBGT. A wet bulb mimics the body sweating to cool as a wet cloth covers the thermometer. A black bulb is used to measure solar radiation taking into account the wind. And a dry bulb is your standard air temperature.
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The resulting temperature is then compared to a chart to provide a level of safety and is more accurate than the heat index. You can see guidelines and risks below when it comes to WBGT for long-distance road races.
'It's key when it comes to running the marathon because we know the level of concern when it comes to weather impacts to the runner,' said Troyanos.
Fortunately, the WBGT for Monday's marathon should stay in the mid to upper 50s.
The wet bulb globe temperature risk chart.
ACSM
Advice for runners
In an average year, three to four percent of the field will need medical attention. It's difficult to plan far out in advance what the weather might be, but the B.A.A. has developed a program to operate swiftly should a surge occur.
There are roughly 30,000 runners in each Boston Marathon, with each athlete hopeful for the weather to work out, or they must plan to adjust their approach come race day.
'It would be wise for runners to learn hand CPR should a fellow runner go down,' said Troyanos. 'It helps bridge the gap until we can help folks.'
Recognize how the weather is on race day versus how you trained and if it is warmer, then run slower to keep your body from overheating. If it's colder, layers will be helpful and listen to your body and take the break to warm up if you need to.
Ken Mahan can be reached at