ironwood

I crossed the country, East to West many years ago, and found September and October to be glorious, but there is no way to predict the weather now. Weather in New England can be as bad as anything out West, especially for a rear round commuter, which I was.


I don't know if the OP has left yet, but looking at the national weather maps, the West looks pretty hot; perhaps dangerously so. I'll take cold over killing heat anytime. I know how to keep warm outdoors, but not how to keep cool.

dgodave

Did you already say where youd be crossing the Rockies at?

indyfabz

ACA’s Trans Am route, so ID, MT, WY and CO. The first crossing east to west is 11,500+’ Hoosier Pass outside of Breckinridge, CO.

Steve B.

Beceause everybody here is aware that at 10,000 ft over some passes, in Sept. and especially in October, you can get enough snow to close you down for a day or more. Maybe didn't happen to you, great.

dgodave

Odds are, no problem. But snowstorms do occasionally strike that time of year in the CO Rockies. My sense is its well worth chancing it. But everybody's risk tolerance is different.

jamawani 

SW Colorado - Mesa Verde NP - El. 7100 ft.
94 yr. Averages
SEP - Hi 76.4F, Lo 48.7F, Snow 0.1 in.
OCT - Hi 64.5F, Lo 38.3F, Snow 1.3 in.

NW Wyoming - Yellowstone NP - El. 7300 ft.
112 yr. Averages
SEP - Hi 64.2F, Lo 29.4F, Snow 1.7 in.
OCT - HI 51.1F, Lo 22.2F, Snow 7.6 in.

staehpj1

These days it seems like we often get way worse than the averages and records seem to fall frequently. I like to plan for comfort in average conditions, but you also need to think about survival without too much hardship in record conditions.

mev

As far as averages go, I like to use weatherspark.com which also gives 75% and 90% percentile bands for temperatures. In general, I look more at the 90% percentile band and make sure I am set for that. There still can be outliers beyond that of course, but when those situations happen, I resort to other fallback methods like waiting out worst weather, rerouting on the fly, etc.

With that said, weather in mountains can always be volatile, but I pay particular attention in shoulder seasons for early/late storms.

staehpj1

I tend to use those as well. I don't necessarily plan for comfort at the 90 percentile numbers, but it is important to be at least safe at them. Survival and keeping all your fingers and toes at an absolute minimum

GamblerGORD53

I would just ride if it's a nice day. 2 easy days to get used to the load, if going hwy 30 or 47. No idea of those road conditions myself.
I rode the Can/Am NW in 2018, was in Astoria on July 7. I then rode a short day to Seaside. There's a bugger steep climb going to Cannon Beach. I went up it with some walking and then said forget it to going down to the ocean and back to Seaside. LOL. From there to Forest Grove was 65 miles or so on hwy 26, 1 steep and 2 moderate climbs I think. Maybe 15 miles with slim or none shoulders, half is thru forest. Was pretty easy riding thru Portland, not counting the hills. LOL. I guess it's 45 miles from Forest grove to the airport. Not saying it's where you sould go.
Getting to CO mtn tops in late Sept. is iffy IMO.

cyccommute 

That depends. As the month of September progresses, the chances of snow is greater. The chances of a paralyzing snow storm is next to zero. Even into October the amount of snow that might fall is rather low. This article gives some feeling to what to expect in Yellowstone. Here’s the same data for Breckenridge. That is a shorter term average than previously presented and reflects current conditions better. Bottom line: you’ll experience cold temperatures (32°F or lower) but probably not snow.

On a positive note, afternoon thunderstorm activity is significantly reduced in September. They can still happen (just like it can still snow) but they are less intense and less prevalent.

dgodave

Yeah, on average I think Sept is better than high summer in CO for weather and for car traffic.