Rinjani mountain is regularly open for Visitor starting April 1st until December 31st every year. Normally light rain already falls on November and December but still safe for trekking. To make sure your comfortable adventure here is the preparation that you need to do before trekking. 1. Make sure you fit and healthy Trekking on rain can be more challenging. Prepare yourself; do exercise, pack extra medicine for cold and fever, ask for doctor advice if necessary. 2. Good grip & Waterproof Shoes On rainy season, the trails will be slippery on few spots. Good grip shoes are necessary to make sure your safety and waterproof shoes for your comfort. 3. Rain coat Choose rain coat that easy to use and can cover full body and the backpack. Use Avoid using pure plastic material, you will make many movements, this material will easy to break. Use combination of fabric and rubber material. 4. Easy dry clothes. Even if it's not raining, walking through the forest and the weeds can get you wet from coming into contact with the plants. wearing clothes that dry easily when walking is highly recommended. 5. Warm jacket Even if not rainy season, bring warm jacket is mandatory. The temperature at Mount Rinjani can be as low as 2 CC.