Start clicking around here. https://www.coloradoinfo.com/blog/where-try-fat-biking-colorado Not sure which area you're in and what's worth the trip. I know friends that have made it out to Crested Butte for the fat bike championships and it's one big party and a good time to demo with vendors in town. Also, give this a read to see what the locals like. https://forums.mtbr.com/colorado-front-range/fat-biking-near-denver-1098526.html Like others said, I think it can be milder than it is up in MN so conditions may be less stable without a deep freeze for months.
if your MTB is collecting dust in Denver, a fatbike will collect more. there's rarely any snow that stays on the ground and trails long enough for a fatbike there. especially if you're not in the west suburbs. we train on road bicycles all winter on the Frange. or... get in the hills and earn your turns!
I’m in Denver too - weather is fine for year round fun. Man up and bundle up . Ya we get the occasional snowy days but I was riding in Jan and feb last year. Invest in the right gear and you don’t miss a beat. For mtb check out bear creek lake park check out Imi for mini racing and moto x - cheap and fun . Open 8am to sunset daily