The Srinagar–Leh highway through Drass is open roughly from mid-May to early November. Outside those months, Zoji La is buried in snow and the valley is effectively cut off from Kashmir. Summer temperatures in Drass reach around 23°C, which is mild and pleasant — the altitude keeps it cool even in July. Autumn brings clear skies and emptier roads, and is the best time to visit if you can time it.
Winter in Drass is not for casual visitors. Temperatures regularly drop below −30°C and have been recorded as low as −45°C, which is at the extreme edge of what humans survive without heated shelter. The valley makes a credible claim to being the second-coldest inhabited place on earth after parts of Siberia. If you are passing through on the highway, plan to cross Zoji La in the morning: convoys go eastbound toward Drass in the morning and westbound toward Srinagar in the afternoon, and the road closes at 6pm. The one-way traffic system is strictly enforced.