2018 Boston Marathon: Runners may encounter cool, wet conditions
No matter how long runners have trained, weather is always the one variable that remains out of their control.
Despite whatever challenges Mother Nature throws at them, more than 30,000 runners will race 26.2 miles to the finish line of the 122nd Boston Marathon on Monday, April 16.
AccuWeather Senior Meteorologist Kristina Pydynowski said there will be seasonable temperatures along with the threat of rain.

Shadrack Biwott, of the United States, douses himself while running along the course of the 121st Boston Marathon on Monday, April 17, 2017, in Natick, Mass. (AP Photo/Steven Senne)
"Depending on the track of the storm delivering the rain, thunderstorms may also be a threat to runners and spectators," Pydynowski said.
The forward speed of the storm may be slow enough to bring eastern Massachusetts very unsettled to downright nasty weather on Monday, Patriot's Day.
"The potential is there for runners to face a car wash effect with drenching rain and stiff winds from the east and southeast at 15-30 mph," according to AccuWeather Senior Meteorologist Alex Sosnowski.

"Despite the forecast of a late-day or evening high temperature in the upper 50s, temperatures during the race are likely range somewhere between the middle 40s to the lower 50s," Sosnowski said.
A normal high for April 16 in Boston is 56 degrees Fahrenheit and a normal low is 41.
The rain will follow a period of milder conditions for southern New England, while much warmer air surges into the mid-Atlantic region on Friday and Saturday.
The race is broken up into multiple classifications. The first group on the course consists of mobility impaired racers, who will start at 8:40 a.m. The men's elite runners and first wave of participants will start at 10 a.m., about 20 minutes after the women's elite runners. The last wave of participants will begin at 11:15 a.m.
Calm and breezy weather conditions haven't always been the case for Boston Marathon runners.
"The early part of the 20th century had a high number of extreme weather conditions for the race, both hot and cold," AccuWeather Senior Meteorologist Bob Smerbeck said.
Michael McGrane, who is the Boston Athletic Association's (BAA) Running Club coach and has run the past 17 Boston Marathons, said he has experienced many types of inclement weather.
"I think I have experienced a good range of weather conditions over the past 17 years including two years when it hit 90 degrees and the nor'easter year," McGrane said.
"The ideal temperature for a marathon is in the range of 50 to 60 F with low humidity and light to no winds. For the Boston Marathon in April, the sun can be more intense and there is very little or no shade on the course at this time of year so it's ideal to have an overcast or cloudy weather day," McGrane said.
Some of the worst marathon weather happened most recently in 2004 and 2012 when the temperatures hit 90 F on marathon day.
When the temperature exceeds 65, a runner's performance in the marathon can begin to decline due to dehydration, McGrane said.
"The last two years the temperature has been 70 and most of the marathoners from our BAA Running Club were five to 10 minutes slower than their goal time due to the warm and sunny day. The other extreme was in 2007 when a nor'easter threatened to halt the 2007 Boston Marathon," McGrane said.

The elite female runners pass through Ashland, Mass., during the 111th Boston Marathon Monday, April 16, 2007. (AP Photo/Chitose Suzuki)
According to McGrane, in colder weather, especially when it rains, runners struggle to keep warm and muscles often tighten up, which can slow their pace.
"Wind is another weather factor that can slow a runner's time in a marathon. A headwind can slow a runner's marathon time by five to 15 seconds per mile by creating a force against the runner, whereas a tailwind can improve a runner's pace by five to 15 seconds per mile running with less effort required," McGrane said.
The Boston Marathon is well known to feature variable weather.
"In April in New England, if it's a cold marathon day then it's often a slight to significant headwind with the wind coming off the cooler coastal waters. If it's a warm day, then it's often a tailwind with the warm southwest wind. On a rare perfect marathon day, as was the case in 2011, the weather is cool with a tailwind," McGrane said.
According to McGrane, it happens maybe once every 10 years.