New Delhi, July 25 : Heavy to very heavy rainfall is very likely at isolated places over Himachal Pradesh, Uttarakhand, east Rajasthan, west Madhya Pradesh, Arunachal Pradesh, Assam, and Meghalaya on Monday, as per the India Meteorological Department (IMD). It has also predicted heavy rainfall at isolated places over Uttar Pradesh, Bihar, sub-Himalayan West Bengal, Sikkim, Nagaland, Manipur, Mizoram, Tripura, Gujarat, central Maharashtra, Konkan, Goa, coastal Karnataka, Kerala and Mahe for Monday. Thunderstorm, accompanied with lightning, is very likely at isolated places over Bihar, West Bengal, Sikkim, Odisha, Arunachal Pradesh, Assam, Meghalaya, Nagaland, Manipur, Mizoram, Tripura and Tamil Nadu, Puducherry, and Karaikal, the IMD said in a release. Warning of an increase in rainfall activity over Western Himalayan Region and adjoining plains of northwest India from Monday, the IMD said that fairly widespread to widespread rainfall with isolated heavy to very heavy falls is likely over Himachal Pradesh and Uttar Pradesh during July 26 and 29, over Uttarakhand during July 25 and 29 and over Jammu & Kashmir, Ladakh, Gilgit-Baltistan & Muzaffarabad, Punjab, and Haryana from July 27 till 29. Enhanced rainfall activity with fairly widespread to widespread rainfall and isolated heavy to very heavy falls likely over Odisha, Gangetic West Bengal, Jharkhand, and Bihar from July 27, it said. For IMD, heavy rainfall is between 64.5 mm to 115.5 mm, very heavy rain 115.6 mm to 204.4 mm, and extremely heavy rainfall above 204.4 mm. /IANS