Due to a sudden fall in temperature, the risk of swine flu in north India would increase, Dr Anil Garg, nodal officer of swine flu in Chandigarh said on Monday. “To ensure elimination of Influenza ‘H1N1’ virus, we need at least 30 degrees Celsius temperature for continuously seven days”, said Garg. He said since Sunday, there has been a gradual fall in the temperature which varies between, 19 to 20 degrees Celsius, which is quite conducive for the growth of the virus. “Due to unpredictable weather in the last few days, doctors are worried about the possible risk of swine flu in the region and advising the people to remain more cautious for a few days more,” he added.