Risky. Your afternoon flight into SFO will likely be 2 hours delayed due to weather (cloudy or rainy weather which is common in January causes SFO to go from two landing runways to one landing runway). The main issue here is the weather at SFO.
Actually, ASE is far more likely to be a problem. The single direction runway combined with high altitude, frequent storms and an aircraft that wasn't really built for that situation (CR7) means United's ASE schedule is pretty much a joke in the winter. Combine that with United's legendary customer service and you have a fine recipe for a frustrating misconnect. Flying into SFO in the winter only adds fuel to the fire.