Outdoor goals! Bad weather! They do not get along well! I at least am not so desperate as to go ride my bike in the rain or a thunderstorm.
There’s machine readable weather forecasts, quite a lot of them. And forecasts especially for the coming three days they are very accurate. Definitely accurate enough to flatten the road in case of precipitation.
The obvious elephant in the room is the 7 days akrasia horizon. Forecasts tend to enter maybe-land rather quickly once you look past the next three days, let alone a full week. Especially rain is very hard to predict then.
I think this would make a great addition to the premium tier, but maybe to the free tiers as well. Think about it: It saves support from having to deal with the “not legit, today’s weather was a big nope, no way I’m gonna go climb Mt. Everest when it’s snowing!” storm of derailment mails.
Also it would just be a very cool feature and it would make the road smarter and feel more relevant.