Chicago Marathon weather not looking great, other options?

yasss wrote:

dewpoint looks relatively low all day. temps will be up, but not until later in the day, as you noted. i still don't think 60-65 is ideal, but definitely not as bad as some fear.

we'll have to see how the forecast evolves.

Ugggh.

I'm shooting for mid 250s (I know, I'm slow). Looks like ~60 at start and halfway then mid 60s at finish. I'm more concerned about the humidity and sun. Forecast is to still be in the 70% when I finish.

There are four main weather factors to consider: heat, wind, dew point and sun.

Heat is on the high side, which is sub optimal, but won't be terrible.

Sun is looking like it is going to be out, which is great from a "nice day" perspective, but imperfect because it intensifies the feeling of the heat. Thankfully, the heat won't be terrible to start with.

Wind is going to be manageable at less than 10 mph, and at that speed, it might actually have a decent cooling effect.

Dew point (a calculation based on heat and humidity) is really probably the biggest single factor, and you are looking at dew points below 55 the entirety of the race. Dew points under 55 are generally considered to mean that there is no impact on performance.

Some suggest looking at the combined dew point and temp. At 10:00, that combined number is forecasted to be just under 120 and at 11:00 it is forecasted to be 123.

Looking at it that way, we are looking at less than a 1% adjustment to times, and that assumes that you are not heat adapted.

Sure, the direct sun might add some challenges there, but the wind will offset that some by allowing for more cooling.

All in all, while it is not ideal, performance shouldn't be impacted too much., if at all.

http://maximumperformancerunning.blogspot.com/2013/07/temperature-dew-point.html

Smoove wrote:

Looking at it that way, we are looking at less than a 1% adjustment to times, and that assumes that you are not heat adapted.

All in all, while it is not ideal, performance shouldn't be impacted too much., if at all.

1% for a 2:30 marathoner is a 1:30 adjustment. That's pretty big.

For a 2:30 marathoner, you will experience combined dew points of 112 at 8:00, 115 at 9:00 and 119 at 9:00, when your race is already over. That averages out to probably about 115 during the actual time running. That's right in the middle of a .5 to 1.0% adjustment, so we are talking about as little as a :45 adjustment, and at most a 1:30 adjustment over ideal conditions.

My guess is that most people have not established their goals assuming ideal conditions, or run their indicator workouts or raced their indicator races in ideal conditions. I am thinking that these conditions will actually be better than the conditions that most people trained through the summer in. And I think the cooling breeze will possibly offset some of the downside of the high temps some.

Yes, I would prefer to see temps around 50 degrees throughout the race, and these are not perfect conditions, but helping to quantify the kind of outside edge of the downside of these conditions will hopefully take the anxiety edge off for some and perhaps help others adjust their goals accordingly.

Honestly, suboptimal, but it could be much worse.

Any scientific studies backing up this 1% at 120 combined DP/Temp, etc.? Or is this something this guy guestimated at?

Love the dynamic... it's always the guy not running the race who is telling those running it that it's no big deal!

Also Skilling from WGN-TV- Chicago (whose forecast I trust more than these others) has the low Saturday night/Sunday morning at 62, so maybe closer to mid-60s at the start of the race.

E. Mutai wrote:

Love the dynamic... it's always the guy not running the race who is telling those running it that it's no big deal!

Also Skilling from WGN-TV- Chicago (whose forecast I trust more than these others) has the low Saturday night/Sunday morning at 62, so maybe closer to mid-60s at the start of the race.

It's a tough beast doing a marathon -- sign up months in advance, train your butt off, hoping all along that race day will bring ideal conditions. Obviously, that's not always the case.

I suffered in Boston this April after some great winter training -- and then hot, sunny conditions.

But honestly, this forecast for Chicago doesn't look too bad from my perspective (granted, I'm not running, which is in line with your point). The idea of bailing on this race and doing a marathon elsewhere seems a bit overly dramatic to me

He didn't cite any sources, so it could be a guestimate, but the numbers seem to be crunched pretty well, and it is generally consistent with some other data that I have seen, which data does seem to cite some studies.

https://runnersconnect.net/dew-point-effect-running/

I hear you, and I have suffered through some tough conditions in marathons (NYC 2014, Boston 2017 (my other marathon - Chicago 2015 was pretty fantastic)); but I am at least citing some hard data here.

And I am not saying it is going to be perfect, but it could be worse. That is not saying that it is no big deal. Plus, why stress all of those who are running out even more? If I hadn't used some reasonable data to support my position, I would get your point more.

I am also from Florida, and most of the people that I am traveling up there to support are from Florida, so for them, I really do think it will be no big deal. For others, I think it will be a manageable challenge.

E. Mutai wrote:

Love the dynamic... it's always the guy not running the race who is telling those running it that it's no big deal!

Also Skilling from WGN-TV- Chicago (whose forecast I trust more than these others) has the low Saturday night/Sunday morning at 62, so maybe closer to mid-60s at the start of the race.

No kidding. There is one in every crowd. Probably the same guy who comes back after warm races and says it wasn't that bad out there. Or when there's a strong headwind says that it didn't affect the race since it didn't feel bad while was spectating.

In 2015 my family waited on the inside corner where the course makes a hard right onto Adams St just before the 13 mile mark. They were within an arms-length of the tangent and all got big high fives. It helped that they were holding one of those noodle things so I could pick them out of the crowd.

I agree the weather doesn't look horrible I think around 10 K you'll know if it's "hot or cold or windy" and then adjust the pace from there.

I definitely will be nervous until we get out there and actually feel what it feels like. I also ran NYC in 2014 and Boston17' it wasn't perfect but tolerable and certainly not the fastest of fast. This doesn't look as bad as those............... so it should be a pretty darn good day :-) I think there's a chance it could be a pretty fast day maybe not perfect but still pretty fast.

*2014 NYC that did suck.

*2016 Boston sucked..... 17 at least it was a tail wind.

Smoove wrote:

He didn't cite any sources, so it could be a guestimate, but the numbers seem to be crunched pretty well, and it is generally consistent with some other data that I have seen, which data does seem to cite some studies.

https://runnersconnect.net/dew-point-effect-running/

no sources there either

Based on Mark Hadley's other "calculations", shouldn't his daughter be running like 2:25 by now?

Mostly just playing. The weather might not be that bad on Sunday.

Experience over 30 marathons tells me that there has to be a floor as far as temperature for the above to be valid. Yes, a lower dew point temp. is going to be a positive but only if the race temperature is under 60 F.

70+ F and with any dew point temp. is going to be murderous for most runners after 20 miles no matter what the charts say.

I recall some retrospective studies that showed that most of the fastest marathon times in the world have been run in temps on either side of 40F.

My heart rate monitor has proven that to be true for me.

A workout above 70F can increase my average by as much as 10% and my resting heart rate is fairly regulated by long term training; can drift down to about 30 beats per minute.

I think that is a fair point, particularly if there is direct sun. I do think that even temps in the high 60s can be manageable with a low dew point for those who are heat adapted.

I went back and looked at Boston this year which was pretty tough, and the starting conditions were what the finishing conditions are forecasted to be for the 3:30 marathoners (I chose that time since that's my wife's goal time). I have to admit that it was uncomfortably warm in Boston. But I do think that the time adjustments estimates were just about right on in my case, by my best estimate.

Smoove wrote:

I think that is a fair point, particularly if there is direct sun. I do think that even temps in the high 60s can be manageable with a low dew point for those who are heat adapted.

I went back and looked at Boston this year which was pretty tough, and the starting conditions were what the finishing conditions are forecasted to be for the 3:30 marathoners (I chose that time since that's my wife's goal time). I have to admit that it was uncomfortably warm in Boston. But I do think that the time adjustments estimates were just about right on in my case, by my best estimate.

Show me fast marathons run in high 60s.

Smoove wrote:

I think that is a fair point, particularly if there is direct sun. I do think that even temps in the high 60s can be manageable with a low dew point for those who are heat adapted.

I went back and looked at Boston this year which was pretty tough, and the starting conditions were what the finishing conditions are forecasted to be for the 3:30 marathoners (I chose that time since that's my wife's goal time). I have to admit that it was uncomfortably warm in Boston. But I do think that the time adjustments estimates were just about right on in my case, by my best estimate.

I agree with this. If you've ever run in 70 degree temperatures with dew points in the 30's, you'll feel like you're running in great conditions. Granted, 70 with 30 dew point is pretty rare, but Smoove makes a very good point. Dew point to me is almost more important than temperature.

I'll add that the MPR calculation for me is spot on, I use it for all my runs in the summer and it's usually within a few seconds of what I actually run.

Jack Daniels has a chart that assigns workload values to compare workouts based upon average heart rate during the workout.

An easy run averaging 70% max heart rate over one hour scores 10 points but the same workout over the same route at around 77% on a warm day is an 18 point effort.

Longer, harder workouts reveal how brutal heat can be in the marathon.

2.5 hours averaging 80% of HR max is a 52.5 point workout but 2.5 hours on the same course with the heart rate at 85% due to higher temperatures requires 90 points of work per Dr. Daniels' research.

The relationship is not linear; there are more points per hour as the HR increases with increasing need for cooling.

The above assumes that the runner has a consistent history of weekly miles so that most easy runs are run at about 70-75% HR max.