Situated on the tropical equator, Lombok Island exclusively experiences two seasons: Dry and Rainy. However, due to its extreme altitude (3,726 meters), Mount Rinjani manifests its own micro-climate. The temperature at the starting villages might hover around 30°C, while simultaneously plummeting to freezing point at the summit.
Dry Season (April - November)
Condition: OptimalHighly Recommended
This is the official trekking window mandated by the National Park. The weather is generally stable with pristine blue skies in the morning, drastically minimizing the risk of landslides or muddy trails.
April - June: Early TransitionThe savannah landscape is lush and verdant post-monsoon. Temperatures are slightly warmer, though brief localized afternoon showers remain a possibility.
July - August: Peak ExpeditionThe most popular season. Rain probability is near zero, making visibility for spotting the entirety of Lombok and Bali absolutely perfect. Nighttime crater temperatures are at their most extreme (coldest) in the annual cycle.
September - November: Late TransitionThe landscape dries out and turns golden brown. Volcanic dust on the Sembalun route becomes quite intense. Towards late November, rain clouds begin to gather.
Total Closure (January - March)
Condition: HazardousIllegal & Prohibited
During these heavy monsoon months, the Mount Rinjani National Park authorities enforce a total closure for all trekking activities for public safety and natural ecosystem restoration.
Storms & Gale-Force WindsExtreme wind velocities in the Pelawangan area can easily blow tents away, accompanied by life-threatening thunderstorms.
Structural Trail FailureMassive torrential rainfall weakens the sandy soil contours, triggering landslide hazards and impassable trails on major routes like Senaru and Sembalun.
Extreme Temperature Dynamics
It is paramount for every trekker to pack adequate technical apparel (layering system). Numerous hypothermia incidents occur due to trekkers' ignorance in responding to the plummeting post-sunset temperatures.
| Camp Location | Altitude | Day Temp | Night Temp |
|---|
| Sembalun / Senaru | 600 - 1.150m | 28°C - 32°C | 18°C - 22°C |
| Forest / Savannah (Pos 2) | 1.500 - 2.000m | 22°C - 26°C | 12°C - 16°C |
| Pelawangan (Crater Rim) | 2.639 - 2.641m | 15°C - 20°C | 3°C - 8°C |
| Rinjani Summit | 3.726m | 5°C - 10°C | 0°C - 4°C |
"Temperatures at 02:00 AM during the Summit Attack strictly mandate heavy windbreakers and thermal insulation layers, compounded by gale winds that make the actual temperature feel below freezing point."
