Indonesia Weather Warning Update June 23-25, 2026: BMKG on Alert for Heavy Rain in 3 Provinces

JAKARTA — BMKG has placed three provinces on Alert for heavy to very heavy rain from Monday to Wednesday, June 23-25, 2026. North Sumatra, the Bangka Belitung Islands, and West Java face the highest risk, while more than 20 other provinces still have rain forecasts that could disrupt daily routines.

The impact is immediate. Residents in the three Alert provinces are being urged to stay away from flash-flood and landslide-prone areas, especially on hillsides and along riverbanks. Strong winds were not included in BMKG’s warning for this period.

Three provinces on Alert

Alert status means the chance of heavy to very heavy rain is high enough to raise the risk of hydrometeorological disasters. The three affected provinces are:

Heavy rain can also come with lightning and localized strong winds, even though BMKG did not issue a large-scale strong-wind warning for this period.

More than 20 provinces face moderate rain

Beyond the three Alert provinces, the risk of moderate to heavy rain is also rising across many other regions. Aceh, West Sumatra, Riau, the Riau Islands, Jambi, South Sumatra, and Bengkulu are on the list. Central Java, East Java, Banten, and West Nusa Tenggara are also included.

East Kalimantan and North Kalimantan are on the radar too. So are Central Sulawesi, West Sulawesi, South Sulawesi, Southeast Sulawesi, North Maluku, Maluku, and all Papua provinces from Southwest Papua to South Papua.

This pattern shows the dry season is not arriving evenly across the archipelago. Large parts of Indonesia are still getting meaningful rainfall, even as some areas are starting to dry out.

Hot midday, rain later in the day

The next three days follow a familiar pattern: clear and hot from morning to midday, with a high UV Index, then moderate to heavy rain likely in the afternoon and evening. BMKG data for Palembang — representing South Sumatra conditions — shows temperatures of 32-33°C with UV Index levels of 8 (Very High) on June 23 and 11 (Extreme) on June 25.

Humidity is expected to range between 62 and 72 percent, with southeast winds at 8-14 kph. The chance of rain in Palembang on June 25 is listed at 10 percent — relatively low — but that figure can look very different in North Sumatra or Bangka Belitung, where Alert status applies.

Very hot.

For people outdoors during the day, BMKG advises protection from UV exposure. Sunscreen with a high SPF, hats, and protective clothing are recommended, especially between 10 a.m. and 2 p.m. WIB.

BMKG advice for Alert areas

BMKG is asking residents in North Sumatra, Bangka Belitung, and West Java to monitor local conditions closely. Avoid standing under weak trees or near poles during thunderstorms. People living in flood zones or on landslide-prone slopes should prepare emergency supplies.

BMKG updates its forecast every six hours through the InfoBMKG app. Residents are advised to check conditions before traveling, especially when crossing mountain roads or routes along riverbanks.

Outside the Alert areas, carrying an umbrella or raincoat is still a smart move. A sudden afternoon shower can still slow down travel and reduce driving visibility.

Warnings continue through June 29

BMKG has also issued an extended forecast for June 26-29, 2026. Moderate rain remains possible in Aceh, North Sumatra, West Sumatra, the Riau Islands, Jambi, South Sumatra, Bangka Belitung, Bengkulu, West Java, Central Java, East Java, West Nusa Tenggara, Kalimantan, Sulawesi, Maluku, and Papua.

The change is in the Alert zone: for June 26-29, Papua Highlands moves into that status with a threat of heavy to very heavy rain. The three current Alert provinces — North Sumatra, Bangka Belitung, and West Java — still need close monitoring because atmospheric conditions can change within 24 hours.

Residents are being told not to rely on a single weather source. BMKG remains the official reference, and six-hour updates help people make better decisions — especially farmers, fishers, and land, sea, and air transport workers whose schedules depend heavily on daily weather conditions.