May to October is the window: dry season, firm trails, clear summit views. July and August have the clearest skies and the biggest crowds, while May and September give you almost the same weather with far fewer people on the trail. The park is closed every wet season, in 2026 from 1 January to 31 March, and December is open but wet and unpredictable.
The dates that matter
Everything else on this page is detail. These six lines decide whether your travel dates work at all.
The two seasons
Rinjani has one long dry stretch and one wet one. The difference between them is not a matter of taste: for three months of the year the mountain is shut.
Dry season
April through November is predominantly dry: settled weather, firm trails and clear summit views. Nights at base camp are 10 to 15°C and days around 25°C, while the summit sits at 0–4°C before dawn.
- May to October is the sweet spot, the driest and most settled stretch, and the window that rewards the 3-day summit and lake trek, where the dawn climb and the crater lake both depend on clear weather.
- 400 trekkers a day. Since April 2026 the park caps entry across the three official routes, with 240 of those places reserved for bookings through licensed operators.
- July and August are the busiest. European and Australian holidays overlap, so those are the months with the most trekkers on the trail.
Wet season
The national park authority (TNGR) closes all official trekking routes every wet season. In 2026 the closure ran from 1 January to 31 March and the season reopened on 1 April. The rain peaks, trails become dangerously slippery and landslide-prone, and the closure gives the ecosystem time to recover.
- The exact dates are announced each year and can shift slightly with the weather forecasts.
- No licensed operator runs treks in this window, and anyone offering one is worth avoiding.
- December stays open, but it is monsoon: heavy rain, mud, swollen river crossings and a real landslide risk on the steep volcanic slopes.
If your travel dates fall in December, talk to the team first. They know current trail conditions and will advise honestly on what is feasible.
Month by month
The mountain is open nine months of the year, and they are not interchangeable. The same season looks different in April than it does in October.
Months to aim for
- April. The park reopens. Trails are fresh and green from the rains, mornings are usually clear, and occasional afternoon showers are possible in the first two weeks as the wet season tapers off. Quiet camps, flexible dates.
- May. Dry weather settles in and skies are clearer than April, while the landscape is still lush. One of the best months for photography, and crowds stay low.
- June. Dry and stable, with excellent trail conditions and comfortable temperatures. European summer holidays start bringing more visitors, so book a week or two ahead.
- July. The driest month. Clear skies almost every day and summit sunrise at its best. Also the busiest: fuller camps and crowded trails near the crater rim. Book well in advance.
- August. Conditions mirror July, and Indonesian Independence Day on 17 August adds to the numbers. The best weather but the least solitude. Book at least two to three weeks ahead.
- September. Summer crowds thin out while the weather stays dry and reliable, slightly warmer than July and August. Peak conditions without peak crowds, and one of the team's personal recommendations.
- October. Still mostly dry, with cloud building in the afternoon as the wet season approaches. Mornings remain clear and there are fewer trekkers. Early October is more reliable than late October.
Months that need a plan B
- November. The transition month. Rain becomes more likely in the second half, trails get slippery, and treks may be delayed or rerouted. Still trekkable, but bring a rain jacket and expect less of the sunrise. Good value, like April and October: see the full trek cost breakdown.
- December. Trekking is possible but significantly more demanding and less predictable. Visibility drops and summit sunrises are often obscured by cloud.
- January to March. The park is shut, all official routes. In 2026 that ran from 1 January to 31 March, reopening 1 April.
"We did it! A very nice trek 3 days / 2 nights with Zain. It was a wonderful experience, a bit hard the second day at 2 am to reach the summit but it was so beautiful when the sun came!"
Picked your month?
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Inside: whether you can actually do this, the month I would pick, how to train for it, and the summit push step by step.
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Zainal, your guideTen years of walking people up this mountain, written down.
Frequently asked questions
What is the best month to trek Mount Rinjani?
The best time to climb Rinjani is May to October, during the dry season. July and August offer the clearest skies but the highest crowds. May and September give the best combination of good weather and fewer trekkers. The park is closed from January through March each year, and December, while open, is wet and unpredictable.
Is it possible to trek Rinjani in December, January or February?
December is possible but demanding: heavy monsoon rain makes trails slippery and muddy, river crossings swell, and summit visibility is often poor. January, February and March are not possible at all: the national park authority (TNGR) closes all official trekking routes for the wet season; in 2026 the closure ran from 1 January to 31 March. If your dates fall in December, contact the guide team first and they will advise based on current conditions.
Which months are least crowded on Rinjani?
April, May, October, and early November are the quietest months on the mountain. July and August are peak season with the most trekkers. May and September offer the best combination of good conditions and low crowds.
What temperature should I expect at the Rinjani summit?
At the summit (3,726 m) before dawn, temperatures typically range from 0 to 4°C, with wind chill making it feel colder. At the crater rim camp (2,641 m), nights are 5 to 10°C. A warm mid-layer, windproof jacket, gloves, and a hat are essential. Sleeping bags are provided.
When does Rinjani National Park close to trekkers?
Rinjani National Park closes every year during the wet season. For 2026 the closure ran from 1 January to 31 March, for all official trekking routes, and the season reopened on 1 April. The exact dates are set each year by the park authority (TNGR) based on weather forecasts, so they can shift slightly. The park can also close temporarily during volcanic activity alerts. Booking with a licensed operator means your permit and dates are checked against the official calendar before anything is confirmed.
Ask Zainal about your dates
There are more trekkers on the mountain in the peak months than in the shoulder season. Tell him your month and group size. He answers personally, usually the same day.