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| Last Updated:: 20/08/2022

Climate

             The climate of Kerala, as per Koppen's classification, is tropical monsoon with seasonally excessive rainfall and hot summer except over Thiruvananthapuram district, where the climate as tropical savana with seasonally dry and hot summer weather. The entire state is classified as one meteorological sub division for climatologically purposes. The year may be divided into four seasons. The period March to the end of May is the hot season. This is followed by Southwest Monsoon season that continues till the beginning of October. From October to December is the Northeast Monsoon season and the two months January & February winter season. The climate is pleasant from September to February. Summer months March to May is uncomfortable due to high temperature and humidity. The State is extremely humid due to the existence of Arabian Sea in the west of it.

 

Wind:The winds over the State are seasonal only in the region of Palghat Gap where winds are predominantly from the east in the period from November to March and from west in the rest of the year. In other parts of the State flow of wind is mainly governed by differential heating of land and water mass together with mountain winds. Winds have westerly component during the day and easterly components during the night through the year. In general winds are quite strong during afternoons when the thermal circulation is best developed and weak during night.

 

Humidity: As the State stretches from north to south with the Arabian Sea in its west, relative humidity is in general high over the State. In the period January to March afternoon humidity reduce to 60-63%, varying from 35% in the interior to 71 % in the coastal area. The diurnal variation in relative humidity during this period is maximum and ranges from 4 to 16%, depending upon the proximity of the sea. The relative humidity in the monsoon period rises to about 85% for the state. The variation in this period is minimum.

 

Temperature:Day temperatures are more or less uniform over the plains throughout the year except during monsoon months when these temperatures drop down by about 3 to 5°C. Both day and night temperatures are lower over the plateau and at high level stations than over the plain. Day temperatures of coastal places are less than those of interior places. March is hottest month with a mean maximum temperature of about 33°C. Mean maximum temperature is minimum in the month of July when the State receives plenty of rainfall and the sky is heavily clouded. It is 28.5°C for the State as a whole in July, varying from about 28°C in the north to about 29°C in the South. Inland stations experience higher maximum temperatures than the coastal stations. From May onwards both the maximum and minimum temperatures start falling, the latter very rapidly while the former slowly.

 

Rainfall: The total annual rainfall in the State varies from 360 cm. over the extreme northern parts to about 180 cm. in the southern parts. The southwest monsoon (June­-October) is the principal rainy season when the State receives about 70% of its annual rainfall. Monsoon rainfall as percentage of annual rainfall decreases from north to south and varies from 83 % in north most district of Kasaragode to 50% south most district of Thiruvananthapuram. Northeast monsoon rainfall as percentage of annual rainfall increases from north to south and varies from 9% in north most district of Kasaragode to 27% in south most district of Thiruvananthapuram. The rainfall amount in the State decreases towards the south with decrease of height of Western Ghats . The southern most district of Thiruvananthapuram where Western Ghats are nearest to the sea coast and its average height is also least in the State receives minimum amount of rainfall. The thunderstorm rains in the pre-monsoon months of April and May and that of monsoon months are locally known as 'EDAVAPATHI'. Rainfall during northeast monsoon season is known as 'THULAVARSHAM' in local language. The southwest monsoon sets-over the southern parts of the State by about 1 st June and extends over the entire State by 5th June. June and July are the rainiest months, each accounting individually to about 23% of annual rainfall.Monthly distribution of Normal and Actual rainfall of Kerala state for last ten years .

 

                  The diversity of the geographical features of the state has resulted in a corresponding diversity in climate. The High Ranges have a cool and bracing climate throughout the year, while the plains are hot and humid. The average level of annual rainfall is quite high when compared to other Indian states. The state basically enjoys 4 types of climate such as Winter, Summer, South West Monsoon and North East Monsoon.

 

Winter Season in Kerala

 

                      In Kerala the winter season starts when the northeast monsoons ends. That is from the month November till the middle of February. During this time, the temperature is less but it does not have much difference with the other seasons. The temperature remains cool constantly throughout the year in the highlands but the winter temperatures falls below 10°C. It is during this winter season that we receive some of the lowest amount of rainfall.

 

Average Temperature during Winter in Kerala:

Maximum: 28°C 
Minimum : 18°C

Average Rainfall during the season :

25 mm

 

 

 

 

Summer Season in Kerala

 

                            The temperature starts to increase with the end of February which indicates the beginning of summer in Kerala. The characteristics of summer in Kerala are relatively higher temperature, less rainfall and humid weather.  The other Indian states have a temperature of about 40°C, whereas in Kerala it is comparatively cool and pleasant. It is mainly because of the presence of the Western ghats that prevents the northern wind from entering our state. The Arabian sea bordering us that gives a cool breeze which helps to make the temperature moderate. Another important feature of this season is the arrival of rain which is accompanied by thunder and lightening. The summer season extends from March till May or the beginning of June. It ends with the beginning of monsoon.

 

Average Temperature during  Summer  in Kerala:

Maximum : 36°C 
Minimum  : 32°C

Average Rainfall during the season :

135 mm

 

 

 

 

South West Monsoon in Kerala

 

                             The rainy season in Kerala is the Southwest monsoon. In malayalam this season is called as Edavappaathi which means in the middle of the malayalam month Edavam.  It is called so because the rain starts by the middle of this month that is the end of May or early June. The following two months have torrential rain. As Kerala lies on the windward side of the Western Ghats and is the first state to get hit by the monsoon winds, this state receives heavy rainfall. It is the monsoon that provides almost 85% of the rains. The slopes of the Western Ghats receive the highest amount of rain. The rivers get flooded by the monsoons. This season continues till the end of September.

 

Average Temperature during this season :

Maximum : 30°C 
Minimum  :19°C

Average Rainfall during the season :

2250-2500 mm

 

North East Monsoon in Kerala

 

                      The North east monsoon is also known as the Retreating Monsoon or the Reverse monsoons. This hits Kerala when the southwest monsoon winds take their return. These rains are called as Thulavarsham in malayalam because it rains during the malayalam month thulam. It comes in the month October and November and at times continues up to December. The main feature of this season is heavy rains during afternoon together with lightening and thunder. The days are usually warm and humid without much variation in temperature.

 

Average Temperature:

Maximum : 35°C 
Minimum  :  29°C

Average Rainfall during the season :

450-500 mm

 

               There has been a great change in the climatic condition of the Earth in the past few years. This has affected the weather conditions in Kerala also. 

 

Average monthly rainfall in Kerala

Month

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Rainfall (mm)

14.6

16.6

36.1

110.9

252.6

653.2

687.2

404.7

252.3

270.7

158.6

45.9

 

 


 

Monsoon 2020

 

                  The pre-monsoon rainfall received in the State from March 1st , 2020, to May 31st , 2020 was normal with a departure of 10.34 percent from the normal. The actual rainfall received during the period was 404.7 mm. Pathanamthitta (856 mm) and Thiruvananthapuram (592.2 mm) Districts received large excess rainfall during the period. Five Districts namely, Kannur, Kasaragod, Malappuram, Palakkad, and Thrissur, recorded deficient rainfall. The percentage departure from normal was highest in Pathanamthitta (73 percent) followed by Thiruvananthapuram (63 percent) and Kottayam (50 percent).

 

                The actual rainfall received in Kerala during the southwest monsoon season (June 1 to September 30th , 2020) was 2246.0 mm as against the normal rainfall of 2038.7 mm which was normal with a departure of 10.2 percent from the normal. During the previous Southwest monsoon (2019), Kerala had received an actual rainfall of 2300.2 mm. Nine Districts in the State received normal rainfall in 2020, while five Districts received excess rainfall, namely, Kannur (3365.9 mm), Kasargod (3605.6 mm), Kozhikode (3440.3 mm), Kottayam (2329.6 mm), Thiruvananthapuram (1153.7 mm). Kasaragod District received the highest rainfall.District-wise Actual Rainfall, Normal rainfall and Percentage of departure for 2020 is given here.

 

South west monsoon rainfall received from June 1 to September 30, 2020

         

       During the northeast monsoon season 2020 (October 1 to November 24, 2020), the State received 314.9 mm of rainfall against normal rainfall of 445.8 mm which was deficient with a percentage departure of (-) 29.4 percent from the normal. Except three Districts namely, Kannur, Idukki, and Kasaragod, all Districts received deficient rainfall. District-wise rainfall distribution in the State in 2020 is given below:
 

Northeast monsoon rainfall received from October 1 to November 24, 2020  

 

                 In 2019, many parts of Kerala were affected by flood, though it was not as severe as in 2018. Compared to 2018, which was a flood year, there were less number of heavy rainfall events in the scale of 75-100 mm in Kerala during the southwest monsoon season of 2019. There were more number of heavy rainfall events in the scale ≥ 100 mm in northern Kerala in 2019 compared to southern Kerala and most parts of central Kerala. During the 2018 floods, southern Kerala was most affected. The heavy rainfall events (≥ 100 mm) were more in southern and central Kerala in 2018. 

 

Monsoon 2021

 

                 The pre monsoon rainfall received in the State from March 1, 2021 to May 31, 2021 was large excess with a departure of 111 per cent from the normal. The actual rainfall received during the period was 772.7mm. All the 14 districts received large excess rainfall. Pathanamthitta (1,342.6mm) and Kottayam (1,049.5mm) districts received highest rainfall during the period. The per centage departure from normal was highest in Pathanamthitta (171 per cent) followed by Thiruvananthapuram (162 per cent) and Kottayam (142 per cent). The onset of South West Monsoon in Kerala was on June 3, 2021. The actual rainfall received in Kerala during the South West Monsoon season (June 1 to September 30, 2021) was 1,729.2mm as against the normal rainfall of 2,038.7mm, which was normal with a departure of (-)15 per cent from the normal. Nine districts in the State received normal rainfall during 2021, while five districts viz, Kannur, Wayanad, Thrissur, Palakkad and Malappuram received deficient rainfall. All the southern districts received normal rainfall. Kasaragod district received the highest rainfall. The details are given below:

 

 

 

 

 

                 During the North East Monsoon season 2021 (October 1 to November 30, 2021) the State received 981mm of rainfall against normal rainfall of 456.6mm, which was large excess with a percentage departure of 114 per cent from the normal. All the districts received large excess rainfall. The departure was highest in Pathanamtitta district followed by Kasaragod district with a deviation of 193 and 146 per cent respectively (figure given below). District wise rainfall distribution in the State in 2021 is given here.

 

 

                 South west monsoon rainfall received from 1st June to 30th September 2021

 

 

 

 

 

Kerala State Action Plan on Climate Change

 

 

Source

Economic Review 2013-2021,  IMD Thiruvananthapuram