The Official Boston Marathon Weather Discussion Thread

angryjohnny wrote:

Run Augur wrote:

I did a rough analysis of finishing times and the weather on past Marathon Mondays days and created a web application that calculates weather-adjusted Boston marathon times. It's at the following link:

https://runaugur.shinyapps.io/boston_marathon_weather_analysis/

Conditions are looking great based on the current Wunderground forecast: 47 degrees at 10 AM with 13 mph winds from the west. I estimate this could take off 5 minutes for a 3hr marathoner!

I like it. Well done.

I'm glad you're enjoying it! Thank you for starting the thread and the inspiration for the analysis topic.

whatsupchucky wrote:

Run Augur wrote:

I did a rough analysis of finishing times and the weather on past Marathon Mondays days and created a web application that calculates weather-adjusted Boston marathon times. It's at the following link:

https://runaugur.shinyapps.io/boston_marathon_weather_analysis/

Conditions are looking great based on the current Wunderground forecast: 47 degrees at 10 AM with 13 mph winds from the west. I estimate this could take off 5 minutes for a 3hr marathoner!

Interesting app, fun to tinker. No way I'd ever adjust my expected pace to be faster. I might consider using it on a warm day to adjust it slower.

Oh yeah; I think there's an error.

Why does it show a faster time if I check the "sunny"?

Running under the sun heats runners up faster and should slow the times down.

Definitely agree with all of that.

The application was for fun and curiosity. A challenge was that I only had the weather conditions for 17 marathons to work with, which makes estimating nuanced aspects difficult. Therefore the predictive model doesn't fully capture the impacts of very high/low temps or head/tail winds. To the sun point after controlling for temperature, I find that a sunny day reduced times. I agree with your assessment though and had the same original hypothesis. I may just remove the sunny option for now until I can better understand it.

Run Augur wrote:

I did a rough analysis of finishing times and the weather on past Marathon Mondays days and created a web application that calculates weather-adjusted Boston marathon times. It's at the following link:

https://runaugur.shinyapps.io/boston_marathon_weather_analysis/

Conditions are looking great based on the current Wunderground forecast: 47 degrees at 10 AM with 13 mph winds from the west. I estimate this could take off 5 minutes for a 3hr marathoner!

Pretty cool, but it predicts faster than goal time no matter which direction is selected for the wind.

Thanks for the cool app.. definitely plan to use it the morning of the Boston marathon to see if I need to adjust my goal time.

Bill Rogers never needed no stinkin' computer App to gauge the weather.

When you run on "Pure Hate" there is no weather inside your head.

M.A.G.A.

Trump2020OP-the real one wrote:

Bill Rogers never needed no stinkin' computer App to gauge the weather.

When you run on "Pure Hate" there is no weather inside your head.

M.A.G.A.

Bill "Rodgers" You're welcome.

I was talking about the lesser known Bill Rogers. He never won Boston, never won New York, never made it to the Olympics, but most importantly never complained about Mother Nature.

M.A.G.A.

Boston Billy wrote:

Trump2020OP-the real one wrote:

Bill Rogers never needed no stinkin' computer App to gauge the weather.

When you run on "Pure Hate" there is no weather inside your head.

M.A.G.A.

Bill "Rodgers" You're welcome.

Then you have my sincerest apology as I have never heard of the lesser known Bill Rogers. Carry on mate;)

It's good, but the wind needs work. For example, with SWS wind, a 30mph barely changes the time.

If you set it to 59-60 degrees (avg. temp) with zero wind and not clear it should be very close to the goal time. That's essentially the average conditions so if there's anything to take away it's those conditions should produce average Boston marathon times.

Run Augur wrote:

angryjohnny wrote:

I like it. Well done.

I'm glad you're enjoying it! Thank you for starting the thread and the inspiration for the analysis topic.

Just curious: Does the app account for dew point/humidity? Is it using the reported conditions in Hopkinton, Boston, or somewhere in between and at what time of day?

Updated forecasts for Marathon Monday. A little bit warmer than yesterday’s forecast...

TWC/wunderground: 48/55, cloudy w 60% rain, SSE 14 mph

Accuweather: 45/55, cloudy w 30% rain, SSW 16 mph

National Weather Service climate map still calling for below average temps thru race day.

angryjohnny wrote:

Just curious: Does the app account for dew point/humidity? Is it using the reported conditions in Hopkinton, Boston, or somewhere in between and at what time of day?

It does not account for dew point. I grabbed the weather quickly from the BAA website rather than research each year on like the NOAA website. They have weather reports from 2000-2017 which nicely coincides with the years where it was easy to grab the marathon results as well (2001-2017).

I took the average of the temperatures in Hopkington and Boston reported by the BAA. So the best input for the model would be the average temperature during the race. I think using the starting temp might be easier though and shouldn't impact the analysis much.

Dril wrote:

If you set it to 59-60 degrees (avg. temp) with zero wind and not clear it should be very close to the goal time. That's essentially the average conditions so if there's anything to take away it's those conditions should produce average Boston marathon times.

This is basically right. I centered the temperature data by subtracting the average temperature. This means the adjustments are made relative to that average so anything warmer or colder will impact the expected time. There is an issue with the app where even with 0 wind speed a wind direction of anything but N or S results an adjustment. I hoping to fix that and the clear sky issue today.

angryjohnny wrote:

Updated forecasts for Marathon Monday. A little bit warmer than yesterday’s forecast...

TWC/wunderground: 48/55, cloudy w 60% rain, SSE 14 mph

Accuweather: 45/55, cloudy w 30% rain, SSW 16 mph

National Weather Service climate map still calling for below average temps thru race day.

I can do without the rain and wind, but will take the temps. :)

FindMyMarathon.com has their Boston Marathon weather app up. You can Insert your finishers time and which wave you are in and tells you what the weather will be at the start hafl and finish plus some other stuff. Looks like they are using TWC/wunderground data according to your list.

Here is their link.

Day 8.5 away. Rainy with NNE winds. Likely to change.

7 days out; rain and wind forecasts aligning against us; temp still okay

TWC/wunderground: 48/53, rain 60%, sse 17 mph

Accuweather: 46/55, rain 75%, sse 17 mph

Rain will suck in Hopkinton waiting for the start.

Rain during the race wouldn't be bad.

whatsupchucky wrote:

Rain will suck in Hopkinton waiting for the start.

Rain during the race wouldn't be bad.

It's a 7 day forecast. They never get it right. It might move through faster and we get Tuesday's weather.