Climate of Pakistan - Factors

Factors

The monsoon and the Western Disturbance are the two main factors which alter the weather over Pakistan; otherwise, Continental air prevails for rest of the year. Following are the main factors that influence the weather over Pakistan.

• Western Disturbances mostly occur during the winter months and cause light to moderate showers in southern parts of the country while moderate to heavy showers with heavy snowfall in the northern parts of the country. These westerly waves are robbed of most of the moisture by the time they reach Pakistan.
• Fog occurs during the winter season and remains for weeks in upper Sindh, central Khyber Pakhtunkhwa and Punjab.
• Southwest Monsoon occurs in summer from the month of June till September in almost whole Pakistan excluding western Balochistan, FATA, Chitral and Gilgit–Baltistan. Monsoon rains bring much awaited relief from the scorching summer heat. These monsoon rains are quite heavy by nature and can cause significant flooding, even severe flooding if they interact with westerly waves in the upper parts of the country.
• Tropical Storms usually form during the summer months from late April till June and then from late September till November. They affect the coastal localities of the country.
• Dust storms occur during summer months with peak in May and June, They are locally known as Andhi. These dust storms are quite violent. Dust storms during the early summer indicates the arrival of the monsoons while dust storms in the autumn indicate the arrival of winter.
• Heat waves occur during May and June, especially in southern Punjab, central Balochistan and interior Sindh.
• Continental air prevails during the period when there is no precipitation in the country.

Pakistan has four seasons: a cool, dry winter from December through February; a hot, dry spring from March through May; the summer rainy season, or southwest monsoon period, from June through September; and the retreating monsoon period of October and November. The onset and duration of these seasons vary somewhat according to location.

The climate in the capital city of Islamabad varies from an average daily low of 2°C in January to an average daily high of 40°C in June. Half of the annual rainfall occurs in July and August, averaging about 255 millimeters in each of those two months. The remainder of the year has significantly less rain, amounting to about fifty millimeters per month. Hailstorms are common in the spring.

Pakistan's largest city, Karachi, which is also the country's industrial center, is more humid than Islamabad but gets less rain. Only July and August average more than twenty-five millimeters of rain in the Karachi area; the remaining months are exceedingly dry. The temperature is also more uniform in Karachi than in Islamabad, ranging from an average daily low of 13°C during winter evenings to an average daily high of 34°C on summer days. Although the summer temperatures do not get as high as those in Punjab, the high humidity causes the residents a great deal of discomfort.