The best seasons for trekking last from April to mid-June, and from October into November. Sunny days abound during these times. Autumn offers the most days with clear blue skies and few clouds. Hiking in the rainy season is not recommended because of the danger of rockfall and mudslides. The monsoon season runs from July through September. You also may want to avoid the first weeks of May and October as these are Chinese national holidays. The area is overrun with trekkers, mountain climbers and other visitors.
Temperatures in the high country can drop well below freezing. Layers of warm clothing and wind and rain protection are essential. A -7˚ C sleeping bag should suffice when lodging at Base Camp. Blankets are available if more insulation is needed.
For weather reports of individual peaks, including Haba Snow Mountain, check out the Mountain Forecast website. You can tailor the report to different elevations, ranging from 2,500 meters to the summit.