The northeast monsoon may have its final spell soon as the Regional Meteorological Centre (RMC) forecasts light to moderate rain mainly over coastal Tamil Nadu till December 28. North Tamil Nadu may see more rain on Christmas Day, while south Tamil Nadu stays dry. Showers will be isolated across the state until Sunday. After a short break, coastal Tamil Nadu and Puducherry might get light to moderate rain on December 30. With dry weather expected in most parts of Tamil Nadu, minimum temperatures may dip 2 to 3 degrees Celsius below normal until Sunday. Chennai will have pleasant, misty mornings and light rain on Thursday. According to B. Geetha, Scientist ‘E’ at RMC, "The easterly winds were picking up speed and may influence mild rain, particularly over north coastal Tamil Nadu and adjoining districts." Minor rainfall activity may also occur on December 30 as per weather models. Dry conditions and stronger radiation cooling, especially in hill areas, could lower night temperatures further, causing ground frost. RMC issued a ground frost warning for isolated areas of Kodaikanal and the higher Nilgiris on Thursday night and early morning hours. Udhagamandalam recorded the lowest minimum temperature of 5.4°C on Wednesday. Kodaikanal and Coonoor logged 7.2°C and 7.4°C respectively. Many plains locations like Salem and Namakkal showed below-normal minimum temperatures, with Tiruttani recording a low of 17.5°C. Since October 1, Tamil Nadu recorded 42.7 cm of rainfall, just 1% below average, which RMC classifies as normal. The official end of the northeast monsoon is December 31, but rain may continue into January, with past monsoons lasting till mid-January, said Ms. Geetha.