The climate of Karachi features an arid climate, albeit a moderate version of this climate. Karachi is located on the coast and as a result has a relatively mild climate. Karachi has two main seasons; Summer & Winter, while spring and autumn are very short. Summer season persists for longest period during the year. The level of precipitation is low for most of the year. Less precipitation during summer is due to inversion layer. Karachi also receives the monsoon rains from July to September. 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. Since summer temperatures (From the end of April till the end of August) are approximately 30 °C (86 °F) to 36 °C (97 °F), the winter months (From November till the end of March) are the best time to visit Karachi. Most visitors, tourists and expatriates come to Karachi during the month of December.
| Climate data for Karachi | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °C (°F) | 32.8 (91.0) |
36.1 (97.0) |
41.5 (106.7) |
44.4 (111.9) |
47.8 (118.0) |
47.0 (116.6) |
42.2 (108.0) |
41.7 (107.1) |
42.8 (109.0) |
43.3 (109.9) |
38.5 (101.3) |
34.5 (94.1) |
47.8 (118.0) |
| Average high °C (°F) | 25.6 (78.1) |
26.4 (79.5) |
28.8 (83.8) |
30.6 (87.1) |
32.3 (90.1) |
33.3 (91.9) |
32.2 (90.0) |
30.8 (87.4) |
30.7 (87.3) |
31.6 (88.9) |
30.5 (86.9) |
27.3 (81.1) |
30.0 (86.0) |
| Average low °C (°F) | 14.1 (57.4) |
15.9 (60.6) |
20.3 (68.5) |
23.7 (74.7) |
26.1 (79.0) |
27.9 (82.2) |
27.4 (81.3) |
26.2 (79.2) |
25.3 (77.5) |
23.5 (74.3) |
20.0 (68.0) |
15.7 (60.3) |
22.2 (72.0) |
| Record low °C (°F) | 0.0 (32.0) |
3.3 (37.9) |
7.0 (44.6) |
12.2 (54.0) |
17.7 (63.9) |
22.1 (71.8) |
22.2 (72.0) |
20.0 (68.0) |
18.0 (64.4) |
10.0 (50.0) |
6.1 (43.0) |
1.3 (34.3) |
0.0 (32.0) |
| Rainfall mm (inches) | 3.6 (0.142) |
6.4 (0.252) |
8.3 (0.327) |
4.9 (0.193) |
0 (0) |
3.9 (0.154) |
66.4 (2.614) |
44.8 (1.764) |
22.8 (0.898) |
0.3 (0.012) |
1.7 (0.067) |
4.5 (0.177) |
167.6 (6.598) |
| Source no. 1: HKO (normals, 1962–1987)[1] | |||||||||||||
| Source no. 2: PakMet (extremes, 1931–2008)[2] | |||||||||||||
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 Karachi city.
Like all other cities, Karachi too has four season which is Winter, Summer, Autumn and Spring. The monsoon season also occurs in Summer. The following is a monthly summary of climatic conditions in the city.
In the month of January, the cold conditions continue in the city and sometimes get very cold due to the Western Disturbance. Humidity remains low in January. 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 millimetres (3.52 in), which occurred in 1995.[2] On 29 January 2011, an intense but short spell of rain lashed all parts of the city, at least 9 millimetres (0.35 in) rainfall was recorded.[3] The lowest temperature of 0.0 °C (32.0 °F) was recorded on 21 January 1934,[2] while the highest temperature of 32.8 °C (91.0 °F) was recorded on 16 January 1965.[2]
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%. 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.[2] The highest monthly rainfall of 96 millimetres (3.8 in) was recorded in 1979.[2]
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.[2] The highest temperature was again recorded in 2010. Being a hot month there is no rain, yet drizzle can occur rarely. March is the 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 millimetres (5.1 in) rain in 1967, which is March's highest rainfall for the city.[2]
The heatwave of March continues in April as well. Temperatures increase and the weather remains dry and hot. The humidity remains between 65–75%. 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.[2] Rain is rare in this month. The highest monthly rainfall of 52.8 millimetres (2.08 in) was recorded in 1935.[2]
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.[2] The humidity is quite high in this month as well between 70–80%. The traffic remains low during the afternoon due to intense heat. Rainfall remains rare during this month and the sky remains cloudless. The highest monthly rain that occurred was in May 1933, when 33 millimetres (1.3 in) rain lashed the city.[4] In 1999, 2001 and 2010, three major cyclones were formed that came close to Karachi. The 1999 cyclone (the fourth strongest cyclone of the Arabian Sea) hit close to Karachi, while the 2001 India cyclone (the third strongest cyclone of the Arabian Sea) made landfall near the Indian border. Cyclone Phet was formed in May 2010, about 1100 km away from Karachi.
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 3 June 1997.[2] 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[5] 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 millimetres (4.34 in) for June in 2007, which broke all previous records for June. Cyclone Yemyin was a weak Category 1 hurricane;[6] its strongest winds were observed in Karachi, Pakistan on 23 June 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).[7] On 6 June 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 week-long journey. Phet produced a very heavy downpour in the city, which broke the previous record of June 2007. About 152 millimetres (6.0 in) of rain with 35 mph (56 km/h) winds occurred due to Phet.[8] Humidity in June typically remains between 75–85%. In the evening, winds from the southwest blow from the sea, causing light drizzle with cloudy weather.
In the month of 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.[2] The highest monthly rainfall for July was 429.3 mm (16.90 in) in 1967.[2] 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 millimetres (11.20 in) rain was recorded during two days of rain.[9] Six years later on 18 July 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[10] with 40 mph (64 km/h) winds making it the second highest rainfall in 24 hours in the city,[11] killing 20 and injuring 150 people. The city's third highest rainfall of 207 mm (8.1 in) in 24 hours was recorded on 1 July 1977.[2] Humidity in July remains high, usually between 80–90%, causing discomfort to the people specially during rush hour. But in the evening, as in June, 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.
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 millimetres (3.0 in) occurred in the city to break the drought period.[12] On 11 August 2007, a very strong tropical depression produced 191 millimetres (7.5 in) in just two days.[13] Rain continued for three days with intense thunderstorms; another monsoon low produced 80 millimetres (3.1 in) of rain on 22 August 2007[14] with 98 mph (158 km/h) winds.[15] 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 millimetres (5.8 in) of rain was recorded[16] with 106 mph (171 km/h) winds.[17] But history has shown that the monsoon withdraws from Karachi during the final days of August. The highest rainfall for August is 271 millimetres (10.7 in), which occurred in 2007;[18] 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.[2] The city's highest rainfall in 24 hours also occurred in August, on 7 August 1953, which is about 278.1 millimetres (10.95 in) of rain battered the city.[19]
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. There is a slight decrease in humidity, which hovers between 70–80%, 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 millimetres (3.1 in) rainfall was recorded.[20][21] From 12 September evening till 13 September afternoon, 2011 a total of 140 millimetres (5.5 in) occurred in the city that caused urban flooding in almost all parts of the city.[22] The highest rainfall for September was 315.7 millimetres (12.43 in) in 1959.[2][4] The highest temperature was 42.2 °C (108.0 °F) on 30 September 1951 and the lowest temperature recorded was 18.2 °C (64.8 °F) on 23 September 1994.[2]
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 10.0 °C (50.0 °F) recorded on 30 October 1949.[2] 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.[2] 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 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 causes the temperatures to decrease. On 9 November 2010 remnants of Cyclone Jal caused gusty winds in the metropolis.[23] The highest rainfall for November is 83.1 millimetres (3.27 in), which occurred in 1959.[2] 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.[2]
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 millimetres (2.50 in) was recorded in 1980.[2] During December 2006 a strong westerly "low" pressure resulted in 60.5 millimetres (2.38 in) of rain in the city.[24] 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.[2]
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 that 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, at about 8 feet below sea level.[25] 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.[26] While another report said that the impact of climate change in Karachi will deepen by 2030[27] Due to global warming the coastline of Karachi is likely to be flooded due to rising sea levels.[28] Many seminars and public gathering are held in the city to make the government and public fully aware of global warming, speakers at the seminar have 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.[29] Karachi also faces the threat from super cyclones which are said to increase their intensity and momentum in years to come.[30]
Cyclones that form in the Arabian Sea do not usually hit Karachi or the Sindh coast, during 1902, 1907, 1944, 1964, 1985, 1999, 2007 and 2010, cyclones made landfall in the Sindh coast including Karachi. Other cyclones that are listed below caused rains as remnants.
| Wettest tropical cyclones/depressions in Karachi Highest known recorded totals |
||||
|---|---|---|---|---|
| Precipitation | Storm | Measurement station |
||
| Rank | (mm) | (in) | ||
| 1 | 245 mm | 9.64 inches | BOB (2009) | Karachi[31][32][10] |
| 2 | 191 mm | 7.51 inches | BOB 06 (2007) | Karachi[13][33][34] |
| 3 | 152 mm | 6.0 inches | Phet 2010 | Karachi[8] |
| 4 | 110.2 mm | 4.34 inches | Yemyin 2007 | Karachi |
| 5 | 43 mm | 1.69 inches | BOB 04 (2007) | Karachi[35][36] |
| 6 | 35 mm | 1.37 inches | Onil 2004 | Karachi[37] |
| 7 | 18 mm | 0.70 inches | BOB 03 (2009) | Karachi[38] |
Most of the flooding in Karachi occurs due to the monsoon season. But due to the enhancement of the city's infrastructure flooding has been controlled. But still excessive and irregular rains can lead to major flooding in the metropolis. Following are some of the major floods in the city;
Drought emerges in the city if the Monsoon season fails to deliver rains then drought emerges. Following are some of worst drought in Karachi city.
Windstorms generally occur when a monsoon system or tropical storms is moving towards the city, However dust storms sometimes occur in winter seasons due to Western Disturbance. Dust storms also occur before the onset of monsoon season, they are locally known as Andhi in the country. Following is a list of windstorms as well as dust storms that occurred in the city, however windstorm generated by a tropical storm is not mentioned in this list.
The average annual rainfall for Karachi is 200 millimetres (7.9 in); the highest annual rainfall of 713 millimetres (28.1 in) was recorded in 1967.[2] Annual monsoon rains for Karachi amount to 146.5 millimetres (5.77 in). The city experienced above-normal monsoon rainfalls in 2003, 2006, 2007, 2009, 2010 and 2011, while in 2004 and 2005 the city received below-normal rainfall. In 2009 the country received 30% below normal rainfall with the exception of Sindh, including Karachi, which received above normal monsoon rains.[52] Karachi has seen record-breaking rainfalls during monsoon season since 2003 with the exception of 2004 and 2005. Following is the annual monsoon rainfall for the last few years based on data from the Pakistan Meteorological Department.[53]
| Monsoon precipitation in Karachi Monsoon begins from June till September |
||||
|---|---|---|---|---|
| Precipitation | ||||
| Year | (mm) | (in) | References | |
| 2000 | 0.1 mm | 0 inches | [54] | |
| 2001 | 63.1 mm | 2.41 inches | [54][55] | |
| 2002 | 123.1 mm | 4.84 inches | [56][57] | |
| 2003 | 355.2 mm | 13.98 inches | [58] | |
| 2004 | 35 mm | 1.37 inches | [59] | |
| 2005 | 80.6 mm | 3.17 inches | [60][61] | |
| 2006 | 236.7 mm | 9.32 inches | [60] | |
| 2007 | 421 mm | 16.6 inches | [53][60] | |
| 2008 | 91.5 mm | 3.60 inches | [60] | |
| 2009 | 439.2 mm | 17.29 inches | [62][63][64][65][66][67] | |
| 2010 | 741.9 mm | 29.21 inches | [8][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84] | |
| 2011 | 436.5 mm | 11.51 inches | [85][86][87] | |