My take away from this thread is pretty well summed up in this post from 'Sunburned Sammy':
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"It was my first Boston and I spent the last five months training in Michigan in temps generally below freezing and in the dark. I found it very warm and my body was not ready for it. I hit the Newton hills just as the sun came out and overheated, along with many other runners.
If I ran in those conditions in September after a summer of training I would probably have done better but it was pretty rough. Almost all runners I spoke with afterwards agreed, although they were also from cold climates."
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Though all of the dew-point and related weather information is interesting—I ran a couple of times last summer, late in the day, with the dew point at 74/75 which led to crazy sweating—For me, it's all about what you're used to.
Like me, here in Ann Arbor, MI, . . . he's been doing most of his running in freezing weather in the dark. I know from experience what it's like to change that up dramatically from one day to the next (or next).
For many years, I ran a weekly 7-mile tempo run around a local state park called Brighton Recreation Area. Though hilly, I always ran hard, feeling like I was flattening the hills with hardly any effort . . . and never even thinking about stopping until I was done. One year, in February or March, we caught a day that reached into the low 80s, when we'd not been even close to that yet. That was a day I'd scheduled to head out to Brighton. About three miles in, I just stopped. It caught me off guard. I hadn't felt particularly awful, I just stopped. I started running again, and it happened again. I stopped. Again. And again. And again. Although I finally finished the run, I reckon I stopped upwards of 15 times. My body just wasn't ready to handle 80 degrees and full sun.
I've run Boston twice. The first year was hot and sunny. I was 21 and had qualified for Boston just a month before in West Bloomfield, Michigan . . . which I ran on a cool, overcast, drizzly morning in March. In Boston, a race official pulled me off the course around 10 miles, telling me that it looked like I was having trouble with the heat. He put me in a lawn chair in the shade, gave me a beer, and told me to watch for the bus coming by to pick up stragglers. I sat there, thinking 'I didn't come all the way to Boston to sit and drink a beer in the shade.' I got back on the course and managed to finish the race. Funny how memory can distort reality. For many years after, I recalled my experience as shuffling in, running maybe around four hours. Last year, I came across my finisher's certificate. I'd actually run 3:14 . . . even with my 'layover.' Youth can forgive much.
Two years later, Boston was cool, overcast, and drizzly. I was ready for that. :-) That's typical early-spring Michigan weather.
Good thread! Congratulations to all of you who ran Boston this year. :-)