Rain and thunderstorm in different parts of the country over the last few days will continue for a few more days, the Meteorological Forecasting Division said on Thursday.

Most places in the hills have received isolated rainfall preceded by thunderstorm since Monday evening. Meteorologist Min Kumar Aryal said, “Active pre-monsoon cloud burst has caused this phenomenon. It is likely to continue for at least one week more.

“Pre-monsoon has been active over the last few days. The atmospheric system is not strong, but the westerly wind has slightly affected the system, causing rainfall in different places.”

In Nepal, the pre-monsoon period falls between March and May. The country receives 12 to 13 per cent of its rainfall in this period while the monsoon season accounts for 80 per cent.Progress of pre-monsoon rain is slow this year.

“One month of pre-monsoon has already gone by. Rainfall was less in the beginning. It has increased slowly with the change in weather from clear to cloudy accompanied by gusty wind and isolated rainfall,” said Aryal.

The pre-monsoon rain has already crossed its mean level for the month of April in Kathmandu, he said.Kathmandu Valley has received 17.5 mm rainfall in the last 24 hours. It has already received 61mm rain so far, exceeding its mean level.

The pre-monsoon phenomenon, which generally affects the hills in the central and western part of the country, slowly starts moving towards eastern Nepal.“We see active pre-monsoon in March and April in western and central region. Later, 

it travels towards eastern Nepal. This forms favourable conditions for the arrival 

of monsoon proper,” said Aryal.

Cloud formation over local areas triggers precipitation, mostly isolated during pre-monsoon period. If local wind merges with westerly wind, the amount of rain could be more, he said.Morning hours remain bright and sunny over the last few days. Dark clouds start gathering late afternoon. The temperature drops as rainfall occurs.