Chennai, Oct 15 : Pre-monsoon showers are to continue in Tamil Nadu till October 18, according to the Indi Meteorological Department (IMD). The rain activity has gained momentum in the state after back-to-back cyclonic circulations forming in the Bay of Bengal and adjoining Andaman Sea. Isolated heavy rains are likely over Tamil Nadu, Puducherry, and Karaikkal till October 18. The cyclonic circulation lies over west central and adjacent Southwest Bay of Bengal in lower tropospheric levels and another cyclonic circulation will form over the Andaman Sea around October 18. The northeast monsoon is likely to touch Tamil Nadu shores in the last week of October. Meanwhile, rains continue to lash Erode, Salem, Kallakurichi, and Tiruvannamalai districts of Tamil Nadu. Around 100 people were evacuated to relief centres in Erode district after heavy rains led to the inundation of their homes. /IANS