Mt. Shasta to Susanville

About the third week of Sept. will be making our
way from Oregon to Carson City via the routes that connect Mt. Shasta, Ca., and Susanville, Ca. Was wondering if weather might
be a factor in the higher altitudes?

Traveled that route many times. No issues. Weather is usually great with high pressure, mild temps, and visibility 50-100 miles. On that route there really are no 'higher alititudes'. Farther south passes are 7000 -10,000 feet and even in the summer it can snow occasionally. It never last long and is not an issue. But the route you have selected is relatively low compared to other Sierra crossings. Wind is much more of a concern between Reno and Carson City.