Heavy rainfall lashed several parts of the national capital Delhi last evening bringing the mercury several notches below normal. According to the Met department, the city also witnessed heavy overnight showers. The maximum temperature dropped three notches below normal to settle at 31.1 degrees on Sunday.The city has received a total of over 435 millimeters of rainfall this season which is almost 20 percent below normal. The Met office however says that the south west monsoon has gained momentum in its last leg and the deficiency is likely to be reduced.Rain and thundershowers will continue in some areas today as well with the mercury likely to oscillate between 32 and 25 degree Celsius.