What makes this area attractive for trekking is the settled weather encountered during the summer months. However, mountain weather is variable, rain (and even snowfall on the passes) could be encountered at any time although this is generally rare and a lightweight waterproof should be adequate.
In the mountains day temperatures are about 20°C. At night, especially at the highest campsites there might be slight frosts. On the other hand, in towns, afternoon temperatures often rise to above 30°C.
If you are already a hiker or backpacker you will probably have much of the clothing and equipment required. A three season sleeping bag and 25 liter rucksack should be adequate. Mules will carry all communal equipment and most of your main luggage. A detailed equipment list will be sent with confirmation of booking.