Almost 100 people have died in the continuous heavy rain and flood that ravaged these four states.
The monsoon fury continued unabated in Karnataka and in neighbouring Tamil Nadu, with the latter pressing the IAF to rescue stranded people from the worst-hit Avalanchi in Nilgiris district.
In Maharashtra, where the death toll stood at 30, the flood situation was improving, according to state-run All India Radio, though authorities said it would be hard to restore rail services in some flood-hit areas within the next two weeks.
The weather agency predicted heavy rainfall at isolated places over Lakshadweep, North Interior Karnataka, Madhya Maharashtra, Himachal Pradesh, Uttarakhand, Rajasthan and Andaman and Nicobar Islands, said the ANI report.
Heavy rain is continuing in Wayanad, hampering the rescue efforts, the officials said. People living in the downstream of the dam have been moved to relief camps. Landslides have also contributed to the death toll. Mr Shah's visit comes as the state government draws criticism from opposition parties for its failure to form a cabinet, more than two weeks after Chief Minister BS Yediyurappa was sworn in. "So we need to remain vigilant", Chief Minister Pinarayi Vijayan said, after a high-level meeting at the State Emergency Operations Centre here.
They also said there was slight reduction in the water level in the Netravati river in Dakshina Kannada district.
Maharashtra Chief Minister Devendra Fadnavis, on Saturday, attributed the flooding to "unprecedented" rainfall this monsoon, which was "more than double" of that in 2005 when massive floods had been witnessed.
"A total of approximately 10,000 persons have been rescued and more than 17,500 persons have been evacuated from the marooned and flooded areas".
Over 30 people are feared missing after a landslide hit Kavalappara in Malappuram district on Thursday.
Volunteers, local residents and members of National Disaster Response Force (NDRF) search for survivors in the debris left by a landslide at Puthumala at Meppadi in the Wayanad district of the Indian state of Kerala.
With heavy rains throwing life out of gear in Kerala, Prime Minister Narendra Modi on Friday assured former Congress President Rahul Gandhi all help for those affected by the flood situation.
Almost 2.5 lakh people have been evacuated in Sangli, Kolhapur and Pune, divisional commissioner Deepak Mhaisekar said.