ISLAMABAD, March 16: The phenomenon of four seasons has almost diminished in the plain areas of Pakistan as the expanded summer has swallowed major portion of spring season.

According to Dr Ghulam Rasool, the chief meteorologist at the Pakistan Meteorological Department, the shortened spring season in the weather map of Pakistan was an indication of the effects of global warming.

The period of spring, which used to span to over 40 to 45 days between March and mid-April in the past, has now reduced to merely less than two weeks, he said.

With the end of winter rains in the beginning of March, the blistering sunshine took the mercury to over 30c in plain areas all over the country. Usually, spring temperatures in the plain areas ranged from 20 to 22 degrees Celsius in the past. Dr Rasool explained that the month of December, which was once considered as colder, has now become warmer. Likewise, January being the snowing month was drifted towards February which remained the coldest period of winter, he added.

In fact, the expanding summer has pushed autumn towards winter swallowing the early period of the cold season.

Except hilly areas, including northern parts of the country, temperature has started rising to cross 30c all over the country. Cold nights have become pleasant, as the use of woollies during daytime has become uncomfortable.

The shortening of spring season will not only affect the horticulture but is also feared to damage agriculture. Wheat is the leading crop of the Rabi season and its harvesting is carried out from March to June. In Sindh, harvesting commences in March while in the plain areas of Punjab, it begins after mid-April. However, in the Potohar region, which accounts for 10 per cent of the total wheat crop, harvesting starts in mid-May.

A wheat plant requires both cold and warm temperature to produce maximum yield. According to agricultural experts, adverse weather conditions, particularly rain, can damage the standing crops which are in final stages of maturing.

In the case of horticulture, the period of seasonal flower plants has also been altered. Horticulturists now need to plan sowing of flower plants early to get full bloom during the shortened period of spring. In federal capital, spring flower beds on roadsides and intersections are yet to give the spring look at a time when summer season is already in place.

Arif Mahmood, the director general of Pakistan Meteorological Department, when contacted, told Dawn that three seasons were now virtually prevailing in most parts of the country. The summer season has started early to expand its duration while the actual spring season is now almost vanished, he said.

However, the Met Office chief forecast that there would be a short span of rainfall - for three days - in the northern part of the country from March 18 that would have some impact on the overall weather conditions of the country.

According to the Met Office, the prevailing dry weather is likely to continue in plain areas of the country during the current week. The day temperatures are increasing gradually in most parts of the country and a heatwave of moderate intensity is likely to grip southern parts of the country.

Most parts of Sindh, southern Balochistan and southern Punjab will remain under the grip of heatwave during next three to four days. Day temperatures are likely to range between 41 and 43c in most parts of Sindh, southern Balochistan, 38 to 40c in southern Punjab and 34 to 36c in Islamabad, upper Punjab and plain areas of Khyber Pakhtunkhwa.

The Met Office stated that the heatwave conditions were likely to subside from coming weekend, after some rain over northern parts of the country.