In a very bizarre event that took place on Monday, a Vistara Flight from Mumbai to Delhi diverted to Lucknow because of bad weather after hovering around the country's capital for about an hour.   

Reportedly, the Mumbai-Delhi flight UK944  which had 153 people on board managed to land the plane just 10 minutes before running out of fuel in Lucknow. The pilots of the flight declared a "Fuel Mayday", due to the seriousness of their situation to the Air Traffic Control of Lucknow.  

Source: Intoday

A spokesperson added,   

The pilot who was operating UK944 flight and issued a 'Mayday' call on Monday has been grounded by the Directorate General of Civil Aviation (DGCA). The unexpected drop in visibility at the destination alternate was the main reason why the aircraft ended up in a low-fuel situation despite carrying excess fuel over and above the required Flight Plan Fuel as per regulations. Safety of passengers and crew was kept at the highest priority throughout the flight. 

Apparently, diversion towards Lucknow was not quite easy as the city's visibility suddenly dropped and a safe landing was not possible. The crew considered a landing at Kanpur and Prayagraj, which comparatively had better weather conditions.   

Source: Holidify

A spokesperson mentioned

En route to Prayagraj, Lucknow ATC then informed the crew that the weather in Lucknow had improved significantly, following which the crew decided to return to Lucknow due to better passenger and aircraft support there. The unexpected drop in visibility at the alternate destination was the main reason why the aircraft ended up in a low-fuel situation despite carrying excess fuel over and above the required Flight Plan Fuel as per regulations. Safety of passengers and crew was kept at the highest priority throughout the flight. 
Source: yimg

Reportedly, the pilot who called "Mayday" has been grounded by the airlines. The pilot has been "de-rostered" as per the instructions of the regulator.