Cyclone Arnab Nepal warnings are now in force, and anyone with an active building site should plan the week around them. The Department of Hydrology and Meteorology (DHM) issued a special post-monsoon bulletin on Monday, October 26, saying a cyclone in the Bay of Bengal is likely to bring rain, thunderstorms and strong winds to much of the country from Thursday, with the heaviest spell on Friday and Saturday. If you are pouring concrete, laying bricks or waiting on a material delivery, the next three days are the time to get ready.
What happened
According to The Rising Nepal, which covered the Cyclone Arnab Nepal outlook, DHM meteorologist Rojan Lamichhane said the cyclone, named Arnab, is intensifying and is expected to become a severe cyclonic storm before it makes landfall near Yanam, between Andhra Pradesh and Visakhapatnam in India, on October 28. The system should weaken as it moves inland, but it is still expected to affect Nepal’s hills and Himalayan region, with the biggest impact in the high mountains.
Cloud cover is expected to build from Wednesday, rain may start on Thursday (October 29), and the system’s influence should begin to fade from Saturday night (October 31). Kathmandu Valley is also expected to be affected.
Key details of the Cyclone Arnab Nepal forecast
- Most affected provinces: Moderate rain with thunderstorms, lightning and strong winds is likely at many places in Koshi, Madhesh, Bagmati and Gandaki on Friday and Saturday, with heavy rain at a few places.
- Western provinces: Some places in Lumbini, Karnali and Sudurpashchim may see moderate rain, and heavy rain is possible at a few locations.
- Rivers: Water levels are expected to start rising on Thursday in the Narayani, Koshi, Bagmati and Kamala basins. On Friday and Saturday, flows could approach warning and vigilance levels in the Narayani, Koshi, Bagmati, Kamala and Tinau basins, with smaller rises in the Mahakali, Karnali, West Rapti and Babai.
- Highest-risk areas: DHM says the main hazards are in the hilly, Chure and Terai catchments, where small rivers and streams could cause flash floods and waterlogging.
- Mountains: In the Cyclone Arnab Nepal bulletin, heavy snowfall, snowstorms and avalanches are possible in the high hills and Himalaya. Tourists have been told not to travel to high areas.
- Other impacts: Colder weather, landslides along roads, and disruption to road and air transport are possible. Farmers were asked to finish harvesting paddy before Thursday.
Why Cyclone Arnab Nepal rain matters for homeowners
Late October is normally dry, so many families restart building work after Dashain. A sudden two- or three-day storm can undo that work. Heavy rain on a freshly cast slab can wash out cement paste from the surface and leave it weak and dusty. Wet cement bags harden and become useless. Open foundation trenches can fill with water, and soft soil at the sides can collapse. Strong wind can topple loose formwork, bamboo scaffolding and stacked bricks.
Roads matter too. The bulletin warns of landslides and transport disruption, and many hill and Chure roads are still being repaired after this year’s floods. If sand, aggregate or steel is stuck on a blocked highway, your mason may sit idle, and you will still pay wages. Our earlier report on Nepal’s expanding flood warning system explains why river-side plots in the Terai need extra care during spells like this.
The good news is that the forecast gives about three days of notice. That is enough time to finish small jobs, cover materials and reschedule the risky ones before Cyclone Arnab Nepal rain arrives.
What to do next: a Cyclone Arnab Nepal site checklist
- Move concrete pours. Avoid casting slabs, beams or roof concrete from Thursday to Saturday. If a pour is already planned for Wednesday, make sure plastic sheets or tarpaulins are ready to cover it.
- Protect cement. Store bags on a raised wooden platform, away from walls, under a roof or a well-tied tarpaulin. Use older stock first.
- Cover fresh brickwork. Put sheets over the top of new walls so rain does not wash out fresh mortar.
- Drain excavations. Cut a small drain or keep a pump ready for foundation pits, and do not let workers stand in deep trenches during heavy rain.
- Secure the site. Tie down formwork, scaffolding, roofing sheets and anything the wind can lift. Stop work on roofs and exposed steel during thunderstorms because of lightning.
- Plan deliveries. Order materials early or delay delivery until after Saturday. Check current rates on our construction materials cost estimator so a rushed order does not cost you more than it should.
- Follow official updates. Watch bulletins from the Department of Hydrology and Meteorology, especially if your plot is near a stream in the Chure or Terai.
FAQ
When will Cyclone Arnab Nepal rain start and end?
DHM says rain may begin on Thursday, October 29, will be strongest on Friday and Saturday, and the system’s influence should weaken from Saturday night.
Which provinces will Cyclone Arnab Nepal rain hit hardest?
Koshi, Madhesh, Bagmati and Gandaki are expected to see the most widespread rain, with heavy falls in a few places. Lumbini, Karnali and Sudurpashchim may also get moderate to heavy rain in some areas.
Can I still cast a roof slab this week?
It is safer to cast before Wednesday evening or wait until after the system passes. Fresh concrete needs protection from heavy rain for at least the first several hours, and then steady moist curing.
Source: The Rising Nepal, October 27, 2026. Additional reference: Ratopati, October 26, 2026 and the Department of Hydrology and Meteorology.
Featured image: “Heavy Rain Dhubikhola River Kathmandu City” by Gunjan Raj Giri, Wikimedia Commons, CC BY-SA 4.0.