Delhi is likely to witness thunderstorms, lightning, and gusty winds over the coming days, while Kolkata and several districts across West Bengal are expected to receive light to moderate rainfall accompanied by thundershowers, according to the latest forecast from the India Meteorological Department (IMD).The weather agency has also indicated that the southwest monsoon is steadily advancing across the country, bringing widespread rainfall to southern, northeastern and eastern regions, while parts of north India continue to experience pre-monsoon thunderstorm activity.ALSO READ: Monsoon alert for travellers: Heading to hill stations? Check's IMD rain warning for these statesDelhi likely to get thunderstorms and strong windsAccording to the IMD's latest weather bulletin, a yellow alert is in place for Delhi today with light rainfall during forenoon and night accompanied by thunderstorms, lightning and gusty winds. Light rain with thunderstorms is also expected in Noida, Gurugram, and Ghaziabad today.The IMD has forecast thunderstorms accompanied by lightning and gusty winds across Delhi and adjoining regions over the next few days with wind speeds could reach up to 60 kmph in isolated areas.ALSO READ: Laid off by Oracle, engineer gets 3 job offers in 45 days: Techie shares job strategy that worked for himThe national capital is among several northern and central Indian regions, including Haryana, Punjab, Rajasthan, Uttar Pradesh, Madhya Pradesh and Chhattisgarh, that are expected to experience unstable weather conditions triggered by pre-monsoon systems. While thunderstorms may offer temporary relief from the heat, residents can expect sudden changes in weather, including dust-raising winds and lightning activity.Kolkata to witness rain and thundershowersIn Kolkata, partly cloudy skies, localised thunderstorms and light rainfall are expected through the week. According to the IMD, daytime temperatures in the city are likely to remain around 37 degrees Celsius, which is slightly above the seasonal average. Night temperatures are expected to hover near 29.8 degrees Celsius.Despite the forecast rain, humidity levels will remain high, ranging between 49 per cent and 86 per cent, potentially making outdoor conditions uncomfortable.Yellow alert issued across West BengalThe IMD has placed both South Bengal and North Bengal under a yellow alert through next week.South BengalSeveral districts in South Bengal are expected to witness thunderstorms accompanied by lightning on multiple days. Authorities have warned of possible localised damage in open areas due to lightning activity.No major change in maximum temperatures is expected across Gangetic West Bengal during the forecast period.North BengalNorth Bengal is likely to receive more intense weather activity, with rainfall ranging between 7 cm and 11 cm in some districts.Heavy showers could be accompanied by gusty winds reaching 40-50 kmph and frequent lightning. The IMD has also forecast a gradual drop of 2-3 degrees Celsius in temperatures across sub-Himalayan West Bengal after the next 24 hours.Southwest monsoon continues to advanceThe southwest monsoon has already covered large parts of the southern peninsula. As of June 4, it had advanced over Kerala, Lakshadweep and parts of Karnataka and Tamil Nadu.The IMD said conditions remain favourable for further advancement over Goa, additional parts of Maharashtra, Karnataka and Andhra Pradesh, the remaining regions of Tamil Nadu, central and northeastern areas of the Bay of Bengal, and parts of northeastern India during the next two to three days.Heavy rainfall forecast in several statesApart from West Bengal, widespread rainfall activity is expected across multiple regions.Kerala, Coastal Karnataka and Lakshadweep are likely to receive persistent rainfall, with isolated spells of heavy to very heavy showers. Active monsoon conditions are also expected across Arunachal Pradesh, Assam, Meghalaya, Nagaland, Manipur, Mizoram and Tripura.Sub-Himalayan West Bengal and Sikkim are forecast to witness continued rainfall through the week, while Uttarakhand may experience heavy rain along with isolated hailstorm activity.Heatwave conditions to persist in some regionsEven as rainfall increases across many parts of the country, some regions are expected to remain under heat stress.The IMD has forecast heatwave conditions in Bihar between June 6 and June 8. Parts of Uttar Pradesh could also experience heatwave conditions beginning June 7.Odisha is expected to remain hot and humid despite scattered rainfall, while similar conditions may persist in parts of Coastal Andhra Pradesh, Tamil Nadu and some northeastern states.IMD advises caution during thunderstormsThe weather agency has urged residents in areas under thunderstorm alerts to remain cautious during lightning activity and strong winds.Particular care has been advised for vulnerable groups, including infants, older adults and people with chronic respiratory or metabolic illnesses, as humid conditions combined with fluctuating temperatures could increase the risk of weather-related health issues.