KARACHI WEATHER

SAIMA IBRAHIM
(feedback@pgeconomist.com)
July 11 - 17, 20
11

Weather in Karachi is classified as mild arid. Very low precipitation level is one of its main characteristics. Karachi's weather is influenced by its positioning along the coast of the Arabian Sea, northwest of the Indus River Delta.

Precipitation levels are at a low throughout the year, managing a meager 10 inches annually approximately. Less precipitation during summer is due to inversion layer. The city enjoys a tropical climate encompassing mild winters and warm summers. The humidity levels usually remain high from March to November, while very low in winter as the wind direction in winter is North easterly.

The city's weather is also notable for its hot summers. Summer temperatures (from the end of April till the end of July) are approximately 30 ∞C (86 ∞F) to 40 ∞C (104 ∞F). Karachi also experiences a monsoon season from July to September, when sudden dusk due to reddish cloud cover sets in, while thunder and abundant downpours of rain engulf the city for days. Monsoonal winds blow in from the southwest of India and are characterized by heavy rainfall, bringing with them not only much needed relief from the scorching temperatures that build up for weeks leading up to the monsoon, but devastating disaster, power shortages, flooding and road blockage.

Unfortunately, the city of Karachi is not equipped to handle the monsoons. Weather in Karachi experiences mild winters. The winter months (from November till the end of March) are the best time to visit Karachi. The days are warm and the nights are cool. Temperatures during the day are approximately 27 oC, during the evenings temperatures fall to 10 oC. During January- the coldest month of the year- winds blowing in from Quetta drop temperatures to 5 oC. These winds make their appearance felt for only a few days, and then Karachi weather is back to its pattern.

Most visitors, tourists, and expatriates come to Karachi during the month of December. The monsoon and the western disturbance are the two main factors, which alter the weather over Karachi, otherwise continental air prevails for rest of the year. Following are the main factors that alter the weather over the city.

Western disturbances mostly occur during the winter months and cause drizzle to light showers, temperature also decreases due to it.

Tropical storms usually form during the summer months from late April till June and then from late September till November.

Southwest monsoon occurs in summer from the month of July until September. Monsoon rains bring much awaited relief from the scorching summer heat. These monsoon rains are quite heavy by nature and can cause significant flooding.

Continental air prevails during the period when there is no precipitation in the metropolis.

MONTHLY WEATHER CONDITIONS

Like all other cities, Karachi too has four seasons that are winter, summer, autumn, and spring. The monsoon season also occurs in summer. The following is a monthly summary of climatic conditions in the city.

JANUARY: The cold conditions continue in the city and sometimes get very cold due to the western disturbance in this month. Humidity remains low. Rains do occur in this month but are moderate in intensity, the sky remains overcast for some part of the month. The highest rainfall during this month was 89.3 mm (3.52 in), which occurred in 1995. On 29 January 2011, an intense, short spell of rain lashed all parts of the city at least 9 mm (0.35 in) rainfall was recorded. The lowest temperature of 0.0 ∞C (32 ∞F) was recorded on 21 January 1934, while the highest temperature of 32.8 ∞C (91.0 ∞F) was recorded on 16 January 1965.

FEBRUARY: Until the middle of the month, the cold conditions continue after that the weather becomes mild throughout the month. The sky remains overcast with drizzle or light rain as a result of the western disturbance. Humidity remains between 40-60 per cent. The lowest temperature was 3.3 ∞C (37.9 ∞F) on 11 February 1950 and the highest was 36.1 ∞C (97.0 ∞F) on 25 February 1996. The highest monthly rainfall of 96 mm (3.8 in) was recorded in 1979.

MARCH: Till the beginning of March the weather becomes hot. The lowest temperature ever recorded was 7 ∞C (45 ∞F) on 9 March 1979 and the highest was 41.5 ∞C (106.7 ∞F) on 2 March 2004. The highest temperature was again recorded in 2010. Being a hot month there is no rain, yet drizzle can occur rarely. March is annual spring season in Karachi after winter; spring brings beautiful flowers in the city. Many flowers shows are also held in the city in March. A weather system dumped 130 mm (5.1 in) rain in 1967, which is March's highest rainfall for the city.

APRIL: The heat wave of March continues in April as well. Temperatures increase and the weather remains dry and hot. The humidity remains between 65-75 per cent. The highest temperature during April was 44.4 ∞C (111.9 ∞F), which was recorded on 16 April 1947, while the lowest temperature of 12.2 ∞C (54.0 ∞F) was recorded on 29 April 1967. Rain is rare in this month. The highest monthly rainfall of 52.8 mm (2.08 in) was recorded in 1935.

May: May is the hottest month for Karachi, with temperatures touching 40 ∞C (104 ∞F). The hottest May was on 9 May 1938, when temperatures reached 48.8 ∞C (119.8 ∞F); the lowest temperature ever recorded was on 4 May 1989 when 17.7 ∞C (63.9 ∞F) was recorded. The humidity is quite high in this month as well between 70-80 per cent. Rainfall remains rare during this month and the sky remains cloudless. The highest monthly rain that occurred was in May 1933, when 33 mm (1.3 in) rain lashed the city.

JUNE: The temperatures of May continue through June with a slight decrease. The highest temperature of June was 47 ∞C (117 ∞F) on 18 June 1979, and the lowest was 22.1 ∞C (71.8 ∞F), recorded on 3rd June 1997. In the middle of June, pre-monsoon rains can start to break the heat spell. Storms like tropical cyclones or tropical depressions form close to the sea of Karachi in this month, as in 2007, when Cyclone Yemyin created havoc in the city with strong windstorms of 69 mph and rainstorms killing 200 people. The storm passed near Karachi and hit Balochistan Province; its remnants caused heavy rains for a week in Karachi. The cyclone produced a heavy rainfall of 110.2 mm (4.34 in) for June in 2007, which broke all previous records for June. Cyclone Yemyin was a weak Category 1 hurricane; its strongest winds were observed in Karachi on June 23, 2007 at about 69 mph (111 km/h), winds battered the city in the evening with heavy downpours; the same morning, temperatures reached 44.1 ∞C (111.4 ∞F).

On June 6, 2010, Cyclone Phet came close to the coast of Karachi as a weak tropical depression, at about 50 km away from the city after a weeklong journey. Phet produced a very heavy downpour in the city, which broke the previous record of June 2007. About 152 mim (6 in) of rain with 35 mph (56 km/h) winds occurred due to Phet. Humidity in June typically remains between 75-85 per cent. In the evening, winds from the southwest blow from the sea, causing light drizzle with cloudy weather.

JULY: The monsoon reaches its peak and produces heavy to very heavy rainfall. As in June, the sky remains overcast with only 3 to 4 hours of sunlight a day, with occasional drizzle at night or early morning. Two or three rainstorms that continue for few days are common in this month. The highest July temperature of 42.2 ∞C (108.0 ∞F) was recorded on 3 July 1958 and the lowest temperature was 21.2 ∞C (70.2 ∞F) on 22 July 1997. The highest monthly rainfall for July was 429.3 mm (16.90 in) in 1967. In 2003, the monsoon's low pressure created a flood situation in Sindh province, with continuous spells of rain in Karachi; at least 284.5 mm (11.20 in) rain was recorded during two days of rain. Six years later on July 18, 2009, there was severe flooding due to a tropical depression, in which heavy rainfall of 245 mm (9.6 in) occurred in just four hours with 40 mph (64 km/h) winds making it the second highest rainfall in 24 hours in the city, killing 20 and injuring 150 people. The city's third highest rainfall of 207 mm (8.1 in) in 24 hours was recorded on July 1, 1977. Humidity in July remains high, usually between 80-90 per cent, but in the evening, cool winds blow from the sea in the southwest with light drizzle, making the weather pleasant. In the evenings, cirrus clouds can be seen daily coming from eastern direction, indicating the monsoon's presence in the city.

AUGUST: The weather of August is identical to that of July. One or two weather systems lash the city in this month, causing significant flooding. In 2006, after two years of drought (2004 and 2005), widespread rainfall of 77 mm (3 in) occurred in the city to break the drought period. On 11 August 2007, a very strong tropical depression produced 191 mm (7.5 in) in just two days. Rain continued for three days with intense thunderstorms; another monsoon low produced 80 mm (3.1 in) of rain on 22 August 2007 with 98 mph (158 km/h) winds. The monsoon typically starts to get weak from the last week of August, but still has the potential to cause heavy rains in the city, as on 31 August 2009, when 147 mm (5.8 in) of rain was recorded with 106 mph (171 km/h) winds. The highest rainfall for August is 271 mm (10.7 in), which occurred in 2007; the highest temperature was 41.7 ∞C (107.1 ∞F) on 9 August 1964, while the lowest temperature was 21.0 ∞C (69.8 ∞F), recorded on 7 August 1984. The city's highest rainfall in 24 hrs also occurred on 7 August 1953, which was about 278.1 mm (10.95 in).

SEPTEMBER: The first two weeks of September can have some good rains. After the first two weeks, the monsoon completely withdraws from the city, and the sky remains sunny and dry with slight decrease in humidity, which hovers between 70-80 per cent, and an increase in temperatures. Rain in this month is inconsistent. During the monsoon of 2005, no rain occurred in the city raising the fears of drought but from 12 September till 13 September heavy rainfall lashed the city about 80 mm (3.1 in) rainfall was recorded. On 10 September 2010, a strong low-pressure system approached Karachi and caused a heavy downpour of 78 mm (3.1 in), accompanied by strong gusting winds of 35 mph (56 km/h) that destroyed the roofs of some mud houses. The highest rainfall for September was 315.7 mm (12.43 in) in 1959. The highest temperature was 42.2 ∞C (108.0 ∞F) on 30 Sept 1951 and the lowest temperature recorded was 18.2 ∞C (64.8 ∞F) on 23 Sept 1994.

OCTOBER: October is the driest month in the city. The highest temperature of 43.3 ∞C (109.9 ∞F) was recorded on 1 October 1959 and lowest was 10 ∞C (50.0 ∞F) recorded on 30 October 1949. Morning is hazy and the winds are calm, the sky remains clear with hot conditions. The highest monthly rainfall for October is 98mm, which occurred in 1959. During the year of 2004, the city received no significant rains with the exception of a heavy rain which occurred in October due to Cyclone Onil.

NOVEMBER: November has warm days and cool nights. Mid-November conditions are much like those of October. During the last weeks of November, there is a gradual decrease in temperature and thus winter begins, but it is not that cold. The first weeks of November are typically dry and the last week of November is cold. Showers occur in this month due to the western disturbance and cause the temperatures to decrease. On 9 November 2010, remnants of Cyclone Jal caused gusty winds in the metropolis. The highest rainfall for November is 83.1 mm (3.27 in), which occurred in 1959. The highest and lowest temperatures are 38.5 ∞C (101.3 ∞F) recorded on 2 November 1994 and 6.1 ∞C (43.0 ∞F) recorded on 29 November 1938 respectively.

DECEMBER: The month of December is the annual winter month, but winter becomes more chilly in January. In December, the weather remains cool. The sky remains cloudy for part of the month, causing temperatures to decrease. Rainfalls are common in the city during the month of December due to the western disturbance coming from the Mediterranean sea. The highest monthly rainfall of 63.6 mm (2.50 in) was recorded in 1980. During December 2006, a strong westerly "low" pressure resulted in 60.5 mm (2.38 in) of rain in the city. The highest recorded temperature for December was 34.5 ∞C (94.1 ∞F) on 11 December 2001 and the lowest temperature was 1.3 ∞C (34.3 ∞F), which occurred on 14 December 1986.

IMPACT OF CLIMATE CHANGE

A UK-based climate change expert has warned that there will be an exceptional change in the temperatures in Pakistan as a whole in the coming years, but the province of Sindh will be less affected as compared to the other provinces of the country. Karachi may however face the threat of rising sea levels by the year 2100. The UK-based climate change expert said that climate change could influence monsoon dynamics and cause summer precipitation levels to drop, as well delays in the start of the monsoon season. Another report said that the impact of climate change in Karachi would deepen by 2030. Due to global warming the coastline of Karachi is likely to be flooded due to rising sea levels. Many seminars and public gathering are held in the city to make the government and public fully aware of global warming. Speakers at a seminar urged the government to prepare long and short-term plans to reduce the impact of global warming on natural resources. They said that 0.5 million hectares of fertile land in Thatta district alone (12 per cent of the entire cultivated area of Sindh) was affected by sea intrusion. Consequently, the lives of about 400,000 fishermen families were threatened and they are being forced to migrate to other areas. Karachi also faces the threat from super cyclones, which are said to increase their intensity and momentum in years to come.