The best season to trek from Manali to Leh is typically from mid-June to September. This period is considered summer in the region when the weather is relatively stable, and the snow has melted, making the high mountain passes accessible. The trekking route, known as the Manali-Leh Highway or the Leh-Manali Highway, offers stunning views of the Himalayas, picturesque landscapes, and cultural experiences along the way. During this time, the temperatures are milder, ranging from 15°C to 25°C in the daytime, making it comfortable for trekking. It is important to note that even during these months, weather conditions can be unpredictable, and it is advisable to check the local weather forecast and road conditions before embarking on the trek.