At least 66 individuals have lost their lives in Nepal since early Friday due to relentless rainfall, which has caused flooding and landslides, leading to the closure of major roads and disrupting domestic air travel, officials reported on Saturday.

The death toll is expected to rise, with an additional 69 people missing and 60 injured since Friday morning, according to Dil Kumar Tamang, a home ministry official who spoke to Reuters. Most of the fatalities occurred in the Kathmandu valley, which houses 4 million people and the nation's capital, where the flooding brought traffic and daily activities to a halt.

Rescue workers employed helicopters and rubber boats to assist those stranded on rooftops or higher ground, as some areas of Kathmandu recorded up to 322.2 mm (12.68 inches) of rain in the past day. Most rivers in the Himalayan nation have swelled, overflowing onto roads and bridges, authorities stated, after a nearly week-long delay in the retreat of South Asia's annual monsoon rains brought heavy downpours across the region.

Police were clearing debris and reopening roads after landslides blocked highways in 28 locations, said police spokesperson Dan Bahadur Karki. The earliest respite from the rains might not arrive until Sunday, according to Binu Maharjan, a weather forecasting official in Kathmandu, who attributed the extended rains to a low-pressure system over parts of neighboring India.

"Heavy rains are likely to persist until Sunday morning, and the weather is expected to clear afterward," Maharjan told Reuters. Most central and eastern areas experienced moderate to extremely heavy rainfall, ranging from 50 mm (2 inches) to over 200 mm (8 inches), with moderate levels recorded elsewhere.

International flights are operational, but many domestic flights have been disrupted, said Rinji Sherpa, a spokesperson for Kathmandu airport. The Koshi River in the southeast, which annually causes deadly floods in India's neighboring state of Bihar, was running above the danger level at 450,000 cusecs, compared to the normal figure of 150,000 cusecs, according to one official.

A cusec is a measure of water flow equivalent to one cubic foot per second. The river level is still rising, added Ram Chandra Tiwari, the area's top bureaucrat. Hundreds of people perish each year during the monsoon season due to landslides and flash floods common in the mountainous nation. Authorities reported that at least 254 people have died and 65 are missing in landslides, floods, and lightning strikes since mid-June when the annual monsoon rains began.