Sri Vijaya Puram, Oct. 20: Heavy to very heavy rain (7-20 cm) is likely to occur at one or two places over Andaman Islands and heavy rain (7-11 cm) is also likely to occur at one or two places over Nicobar Islands on Oct. 21. Squally weather with wind speed 35 kmph to 45 kmph gusting to 55 kmph is likely to prevail over Andaman Sea and along & off A&N Islands till Oct. 23. Sea condition is likely to be rough to very rough. Fishermen have been advised not to venture into sea over Andaman Sea and along & off A&N Islands till Oct. 24.