LUCKNOW, May 4 -- A sudden spell of unseasonal rain, thunderstorm and dense cloud cover plunged Lucknow and adjoining areas into darkness on Monday morning, catching residents off guard and sharply reducing visibility across the city.

Lucknow recorded 14.8 mm rainfall within an hour, while the maximum temperature dropped to 29 degrees Celsius, 10.4 notches below normal. The city also logged its lowest day temperature for May in the last four years. The minimum temperature, however, rose to 24 degrees Celsius.

The weather office has forecast partly cloudy skies with thundery development and one or two spells of rain or thundershowers for Tuesday. The maximum and minimum temperatures are likely to hover around 31 degrees Celsius and 21 de...