The weather department has predicted heavy to very heavy rainfall over some areas of the western Himalayan region and heavy rainfall over a few parts of the plains of northwest India during most days of this week.Fairly widespread to widespread rainfall is likely over Punjab, Haryana, Chandigarh and Delhi on August 15 and August 17 and 18, according to a bulletin issued by the India Meteorological Department (IMD) on August 14.A yellow alert has been issued by the IMD in these states for these three days. Isolated to scattered rainfall is likely over the region on other days.The monsoon activity in Punjab and Haryana during the past 24 hours has been termed “weak” by the weather department.Light to moderate rain, along with thunderstorms and lightning, occurred at isolated places in these states, with both day and night temperatures remaining above normal.During August so far, the monsoon deficiency in Punjab has gone up to 42 per cent, whereas it is above normal by 30 per cent in neighbouring Haryana.The seasonal rainfall from June 1 onwards, however, is below the long-period average by 34 per cent in Punjab and 16 per cent in Haryana.The IMD has also predicted fairly widespread to widespread rainfall over Himachal Pradesh, Jammu and Kashmir, Ladakh and Uttarakhand till August 20. Heavy rainfall is also expected at a few places in these states during this period.