Colorado passes in September
 

I am interested in driving from Vail to Santa Fe via Leadville, Salida, and Alamosa.

How late are the passes open over the mountains?

Thanks in advance.

All the passes on the roads you will be taking are open all year. The only time they might be closed is if a huge blizzardy snow storm hit the area and then they might be closed briefly while the road department cleared. It is highly unlikely that it would happen in September.

You have chosen a gorgeous route. The aspen should be golden at that time.

the only pass you are going over is battle mtn. from vail to leadville. it is open year round. when you get to leadville find elm street (last right on the south end of town) and go to 'the grill' for the best mexican food in colo!
just south of salida rte 285 splits off to the west for a few miles. stay on rte 17 - it's straight south to alamosa, where you rejoin 285 to santa fe.

Between Vail and Leadville you will go over Tennessee Pass (10,424 ft). From Leadville to Johnson Village (just north of Salida) Hwy 285 follows the Arkansas River with the Collegiate Peaks to the west and the Mosquito Range to the east - a very scenic drive.
Just west of Salida, Hwy 285 leaves the Arkansas River Valley and heads up to Poncha Pass (9,010 ft), which is easy schmeezy. About 20 miles south of Poncha Pass, Hwy 285 junctions with Hwy 17. 285 heads west, 17 heads directly south. Take Hwy 17! The mountains to the east (your left) that you now parallel all the way to Alamosa will be the Sangre de Cristo mountains.
Barring a freak, early season snowstorm, both passes will be open.

Hi everyone

I'll be following a similar route in early November (the 7th or 8th as a matter of fact). Does a few extra weeks make a difference - could snow be an issue then? I hope not - I really want to visit these towns. I'm also planning on making a side trip into Aspen before heading down into Leadville etc...

October, not November! I don't know why I typed that - I'm heading to Portugal in November (I have Portugal on the brain right now).

I'll be in Colorado in early October.

It probably won't make any difference. But the chance of snow does increase with every passing week. Independence Pass between Twin Lakes and Aspen usually closes mid-November.