With the absence of western disturbances, day temperatures will rise gradually across the country crossing 40 degrees over the next few days, India Meteorological Department (IMD) said Wednesday.In Delhi, the mercury will gradually rise to 42 degree Celsius by April 18.“Maximum temperatures are likely to become above normal over northwest, central and east India during the week. Heat wave conditions and hot & humid weather are likely to prevail over isolated pockets of central, east, west and south India during the week,” the IMD said.The highest maximum temperature of 44 degrees Celsius was reported jointly at Akola (Maharashtra) and Kalaburagi (Karnataka) on Wednesday.  The lowest minimum temperature of 14.5 degrees Celsius was observed at Gurdaspur in Punjab.A fresh weak western disturbance is likely to affect western Himalayan region from the night of April 16. This will lead to moderate rainfall over Jammu & Kashmir, Ladakh from April 16-19 and isolated rainfall over Himachal Pradesh and Uttarakhand on April 17.IMD said the gradual rise in maximum temperatures will be 3-4 degrees Celsius over northwest India during April 15-18. The day temperatures will rise by 2-3 degrees Celsius over the Central India during April 15-20 in the northeast India there will be an increase in maximum temperatures by April 16th April.Heat wave conditions will prevail over Madhya Pradesh, Maharashtra Vidarbha and North Interior Karnataka, Chhattisgarh, Telangana this week.Hot and humid weather conditions will be observed over Gangetic West Bengal, Odisha, Coastal Maharashtra, Andhra Pradesh, Gujarat, Tamil Nadu, Puducherry, Karnataka and Kerala.