When does the rainy season begin in Lombok and Sumbawa?

West Nusa Tenggara’s 2025/2026 rainy season was forecast to begin between the third ten-day period of October and the third ten-day period of November 2025. BMKG’s regional forecast placed Lombok’s onset between the third ten-day period of October and the second ten-day period of November, while Sumbawa was expected to enter the season between the first and third ten-day periods of November.

When was the rainy season expected to begin?

According to the BMKG Stasiun Klimatologi Nusa Tenggara Barat forecast, all 27 seasonal rainfall zones in West Nusa Tenggara were expected to enter the 2025/2026 rainy season between the third ten-day period of October and the third ten-day period of November 2025.

The forecast is regional rather than a single island-wide date. Lombok was forecast to start between the third ten-day period of October and the second ten-day period of November, while Sumbawa was forecast to start between the first and third ten-day periods of November, according to BMKG NTB, 2025.

Why do Lombok and Sumbawa have different dates?

BMKG divides the province into seasonal rainfall zones, so the expected onset varies by location. The agency compared the forecast with the 1991–2020 normal onset and said 20 zones were expected to begin earlier than normal, while 7 were expected to match normal timing, according to BMKG NTB, 2025.

What did BMKG forecast about the wider rainy season?

BMKG forecast that the 2025/2026 rainy season would generally have normal rainfall characteristics, meaning seasonal rainfall was expected to be close to the usual pattern. Nationally, 69.5% of seasonal rainfall zones were forecast to fall into the normal category, according to BMKG, 2025.

What does the climate data show for East Indonesia?

Monthly conditions can differ from the seasonal forecast. The BMKG NTT climatology bulletin reported that rainfall in East Nusa Tenggara in December 2025 generally ranged from 301–400 millimetres per month and was classified as above normal, according to BMKG NTT, 2025.

BPS also maintains tourism statistics for East Nusa Tenggara covering visitor activity, overnight stays, spending, destinations and tourism infrastructure. Those statistics provide a separate official measure of how weather-sensitive travel activity is recorded in the province, according to BPS NTT, 2025.

Sources

• BMKG
• Badan Pusat Statistik Provinsi