A nor'wester is likely to lash parts of Bangladesh, including Dhaka, the Bangladesh Meteorological Department (BMD) said in an update Wednesday.

The update on the BMD app, sent around 10pm, said to expect rain or thundershowers accompanied by temporary gusty or squally winds, or Kalbaishakhi, "in the next 3-4 hours."

A heatwave is sweeping over Sitakunda, Rangamati, Cumilla, Maijdee Court, Feni, Rajshahi, Pabna; and Dhaka, Rangpur, Khulna, Barishal and Sylhet divisions.

Rain or thundershowers accompanied by temporary gusty or squally wind or Kalbhaishaki is likely to sweep over Rangpur, Rajshahi, Dhaka, Mymensingh and Sylhet divisions and Cumilla in the next 24 hours, the BMD said earlier.

Nor'wester or the Kalbaishakhi occurs in India and Bangladesh, often with violent hurricane-speed winds and the pre-monsoon nor'wester is caused by heavy convection for excessive heat.

A severe Nor'wester hit Dhaka and northwestern Bangladesh on April 4, 2015, leaving a trail of destruction – killing at least 24 people and injuring hundreds, uprooting countless trees and flattening many tin built houses and mud-built houses and snapping road and rail communication with affected areas.

Another danger that has come to the fore in recent years is lightning accompanying the nor'westers, that have taken scores of lives in recent years. In 2016, 42 people were killed in a single day of nor'westers across the country.