Thunderclouds five to six kilometres high, described as ``unusually tall'' by the weatherman, resulted in a hailstorm that caught Delhiites unawares this afternoon. The rain and hail forced motorists to switch on their headlights and pedestrians to scamper for shelter.

The downpour comes following a week of bright, sunny days. Over the week, the day has been warm and temperatures have been on the higher side. According to Met Department officials, the South-Westerlie winds that blow in with a western disturbance are preceded by warm weather.

Thunderclouds gathered over the city early this morning. A drizzle began in the early hours. There was a brief respite during rush hour, but the overcast sky was back at noon, complete with ``big balls of snow'' and rain. After half-an-hour of blizzard like conditions, the sun was back, melting the hail and bringing some cheer. Cold winds, however, continued to blow.

The maximum day temperature dropped to 17.2 degrees Celsius, seven degrees below yesterday's maximum of 24.4. The average maximum this time of the year is 21 degrees Celsius. Last year, the lowest maximum recorded was 17 degrees Celsius, 0.2 less than today's temperature.

The minimum, on the other hand, was a high 11.5 degrees Celsius, 3.8 degrees more than the minimum recorded yesterday. There are slim chances of Beating Retreat ceremony being disrupted by showers.