The average annual temperature of a meteorological station is 26oC, its average annual rainfall is 63 cm and the annual range of temperature is 9oC. The station in is

1. Fundamental Factors Influencing India's Climate (basic)

Hello! To understand why India’s weather varies so dramatically—from the snowy peaks of Ladakh to the humid beaches of Kerala—we must first look at the fundamental factors that act as the 'architects' of our climate. These factors determine the temperature, pressure, and rainfall patterns we see across the subcontinent.

The first major factor is Latitude. The Tropic of Cancer passes right through the middle of India. This creates a fascinating divide: the southern half lies in the Tropical Zone, while the northern half is in the Sub-tropical and Temperate Zone. Because the south is closer to the Equator, it stays warm throughout the year with a very small range of temperature. In contrast, the north experiences extreme 'continental' climates—scorching summers and freezing winters INDIA PHYSICAL ENVIRONMENT, Climate, p.29.

Next, we consider Altitude and Relief. You might have noticed that hill stations are cool even in peak summer. This is because temperature decreases as height increases. A classic example is Agra and Darjeeling: they are located on roughly the same latitude, but in January, Agra might be at 16°C while Darjeeling is at a chilly 4°C due to its elevation INDIA PHYSICAL ENVIRONMENT, Climate, p.29. Furthermore, our Relief (mountains and plateaus) acts as a physical barrier. The Himalayas are particularly heroic; they block the freezing Siberian air from entering India and trap the monsoon winds, ensuring the northern plains receive life-giving rain instead of becoming a cold desert Geography of India, Physiography, p.28.

Finally, Proximity to the Sea plays a massive role. Water heats up and cools down much slower than land. This creates a moderating effect for coastal cities like Mumbai or Chennai. They rarely see extreme temperature swings. However, as you move deep into the interior (like Delhi or Amritsar), this influence fades, leading to high seasonal contrasts Exploring Society: India and Beyond, Climates of India, p.65.

Factor	Impact on Climate
Latitude	Determines if a place is Tropical (warm) or Sub-tropical (variable).
Altitude	Higher places (mountains) are cooler than plains.
Distance from Sea	Coastal areas are moderate; interiors are extreme.
Himalayas	Shields India from cold winds and traps moisture.

Sources: INDIA PHYSICAL ENVIRONMENT, Climate, p.29; Geography of India, Physiography, p.28; Exploring Society: India and Beyond, Climates of India, p.65

2. Continentality vs. Maritime Influence (basic)

To understand why a city like Mumbai feels pleasant year-round while Delhi faces bone-chilling winters and scorching summers, we must look at the thermal properties of land versus water. Water has a much higher specific heat capacity than land, meaning it requires more energy to heat up and takes longer to lose that heat. Consequently, oceans and seas act as giant thermal buffers. They heat up and cool down much slower than the land surfaces nearby Physical Geography by PMF IAS, Ocean temperature and salinity, p.517. This creates a moderating influence in coastal regions, often referred to as a Maritime Climate.

In coastal areas, the sea prevents temperatures from reaching extremes. During the day or in summer, the cooler air from the sea moves toward the land (sea breeze), and during the night or in winter, the water retains heat longer, keeping the coastal air mild. This results in an equable climate, characterized by a low Annual Range of Temperature (the difference between the hottest and coldest months). For example, a coastal city might only see a 3–5°C difference between its summer and winter averages INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT), Climate, p.29.

As we move away from the coast into the interior of a landmass, this moderating influence fades away. This phenomenon is known as Continentality. Without the presence of a large water body to absorb or release heat, the land heats up rapidly in summer and cools down just as fast in winter. This leads to extreme climates with a high annual range of temperature. A classic comparison is seen between Mumbai and Nagpur; while both are at similar latitudes, Nagpur experiences much harsher summers and colder winters because it lacks the sea's protective embrace Exploring Society: India and Beyond, Social Science-Class VII NCERT, Climates of India, p.51.

Feature	Maritime Influence (Coastal)	Continentality (Inland)
Temperature Range	Low (Equable/Moderate)	High (Extreme)
Summer/Winter	Mild summers, warm winters	Hot summers, cold winters
Primary Cause	High specific heat of water	Rapid heating/cooling of land

Sources: Physical Geography by PMF IAS, Ocean temperature and salinity, p.517; INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT), Climate, p.29; Exploring Society: India and Beyond, Social Science-Class VII NCERT, Climates of India, p.51

3. Mechanism of Monsoons and Seasonal Rainfall (intermediate)

To understand the Indian Monsoon, we must first look at it not just as 'rain,' but as a massive, seasonal reversal of wind systems. Derived from the Arabic word 'Mausim' (meaning season), the monsoon is a global-scale phenomenon where the atmosphere 'breathes' in and out. In the Indian subcontinent, this is characterized by a complete reversal of wind direction between summer and winter Geography of India, Majid Husain, Climate of India. This happens primarily due to the differential heating of the land and the sea. During summer, the vast landmass of Asia (specifically the Tibetan Plateau and Northern Plains) becomes significantly hotter than the surrounding oceans, creating a powerful low-pressure center that acts like a giant vacuum, pulling in moisture-laden winds from the high-pressure zones of the southern Indian Ocean.

The South-West (SW) Monsoon is the engine of India's rainfall. By early June, the low pressure over the northern plains intensifies so much that it attracts the South-East Trade Winds from the Southern Hemisphere. These winds originate over the warm subtropical oceans, cross the equator, and—due to the Earth's rotation (Coriolis force)—deflect to the right, entering the Arabian Sea and Bay of Bengal as the South-West Monsoon CONTEMPORARY INDIA-I, Geography, Class IX . NCERT, Climate, p.30. These winds are strong, averaging 30 km/h, and carry immense moisture. Upon hitting the Indian peninsula, the monsoon splits into two main branches:

• The Arabian Sea Branch: This strikes the Western Ghats (causing heavy rainfall), moves through the Narmada and Tapi valleys into Central India, and even reaches the Saurashtra/Kachchh region INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT), Climate, p.35.
• The Bay of Bengal Branch: This carries moisture toward the North-East and is deflected by the Himalayas, moving westward along the Ganga plains.

As the sun begins its 'southward march' in September, the Northern Plains cool down and the low-pressure trough moves toward the Bay of Bengal. This triggers the Retreating Monsoon. Unlike the sudden 'burst' of the onset, the retreat is a steady and gradual process Geography of India, Majid Husain, Climate of India, p.25. By October and November, the winds shift to a North-Easterly direction. As these retreating winds cross the Bay of Bengal, they pick up moisture and bring late-year rainfall to the eastern coast, particularly Tamil Nadu and Karnataka INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT), Climate, p.37.

Sources: Geography of India ,Majid Husain, (McGrawHill 9th ed.), Climate of India, p.25; CONTEMPORARY INDIA-I ,Geography, Class IX . NCERT(Revised ed 2025), Climate, p.30; INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.), Climate, p.35-37

4. Rainfall Distribution and Variability across India (intermediate)

The spatial distribution of rainfall in India is characterized by extreme diversity, largely dictated by orography (mountainous relief) and the path of moisture-laden monsoon winds. The national average of about 125 cm is deceptive, as local totals range from over 1,000 cm in the Northeast to less than 15 cm in the desert Majid Husain, Geography of India, Chapter 4, p.30. Areas of very heavy rainfall (above 200 cm) are found on the windward slopes of the Western Ghats and the hills of Meghalaya. For instance, Mawsynram and Cherrapunji receive over 1,200 cm due to the funneling effect of the Khasi hills Majid Husain, Geography of India, Chapter 4, p.30. Conversely, regions like Western Rajasthan, Ladakh, and the interior Deccan Plateau receive inadequate rainfall (often below 50-60 cm) because they either lie in the rain-shadow of mountains or are far from the moisture source NCERT Class IX, Contemporary India-I, Chapter 4, p.32.

Beyond the total volume, rainfall variability is a critical concept for understanding climatic risk in India. Variability refers to how much the actual rainfall in a year deviates from the long-term average. There is an inverse relationship between the amount of rainfall and its variability: regions with very high rainfall (like the West Coast) show low variability (below 15%), meaning they get consistent rain every year. However, regions with low annual rainfall, such as Western Rajasthan and the interior Peninsula, exhibit high variability (often exceeding 50-80%) NCERT Class IX, Contemporary India-I, Chapter 4, p.32. This is why these dry regions are most susceptible to both devastating droughts and occasional flash floods.

The distribution can be broadly categorized into four zones:

• High Rainfall (>200 cm): Western Coast, North-East India, and parts of the sub-Himalayan belts.
• Medium Rainfall (100–200 cm): West Bengal, Bihar, Odisha, and eastern Uttar Pradesh Majid Husain, Geography of India, Chapter 4, p.25.
• Low Rainfall (50–100 cm): Parts of the Deccan Plateau, Punjab, Haryana, and eastern Rajasthan NCERT Class XI, India Physical Environment, Chapter 4, p.38.
• Very Low Rainfall (<50 cm): Western Rajasthan, Ladakh, and the rain-shadow region east of the Sahyadris (Western Ghats).

Sources: Geography of India, Majid Husain, Climate of India, p.30; CONTEMPORARY INDIA-I, Geography, Class IX NCERT, Climate, p.32; INDIA PHYSICAL ENVIRONMENT, Geography Class XI NCERT, Climate, p.38; Geography of India, Majid Husain, Climate of India, p.25

5. Koppen's Classification of Indian Climatic Regions (intermediate)

Vladimir Koppen’s climatic classification is the most widely used system in geography because of its empirical nature—meaning it is based on observable data like temperature and precipitation rather than theoretical models. Koppen recognized that vegetation is the best expression of a region's climate; therefore, he selected specific temperature and rainfall boundaries that aligned with various vegetation zones. In the Indian context, this provides a highly structured way to understand why a rainforest exists in Kerala while a scrub forest exists in Andhra Pradesh Geography of India, Majid Husain, Chapter 4, p.33. To master this, you must first understand the capital letter codes representing broad temperature zones. In India, we primarily deal with A (Tropical), B (Dry), C (Warm Temperate), D (Cold Snow Forest), and E (Polar). These are then modified by lowercase letters that indicate the seasonality of rainfall. For instance, the letter 'w' stands for winter-dry, while 's' stands for summer-dry. This is crucial for India because our rainfall is largely dictated by the Monsoons Physical Geography by PMF IAS, Climatic Regions, p.430.

Symbol	Climate Type	Region in India
Amw	Monsoon with short dry season	Western Coast (Kerala/Karnataka)
As	Monsoon with dry summer	Coromandel Coast (Tamil Nadu)
Aw	Tropical Savanna	Most of the Peninsular Plateau
Cwg	Monsoon with dry winter	Ganga Plains
BShw	Semi-arid Steppe	Rain-shadow of Western Ghats, parts of Rajasthan

A particularly interesting case is the Aw (Tropical Savanna) climate. Unlike the evergreen forests of the Western Ghats, the Aw region has a distinct dry season where vegetation must adapt to water scarcity. This type covers the bulk of the Deccan Plateau. Meanwhile, the As type is almost unique to the Tamil Nadu coast, where the traditional summer monsoon (South-West) stays dry, and rains arrive during the retreating (North-East) monsoon in winter Physical Geography by PMF IAS, Climatic Regions, p.435.

Sources: Geography of India, Climate of India, p.33; Physical Geography by PMF IAS, Climatic Regions, p.430; Physical Geography by PMF IAS, Climatic Regions, p.435

6. Climatic Profiles of Major Indian Cities (exam-level)

To understand why Indian cities feel so different, we must look at their climatic signatures—the unique combination of temperature range and rainfall determined by their geography. The most critical factor is Continentality (distance from the sea). Coastal cities like Mumbai or Kochi experience a maritime influence, where the sea acts as a giant thermostat, keeping temperatures stable year-round. In contrast, inland cities like Delhi or Jodhpur face extreme seasonality, with scorching summers and chilly winters because they lack this moderating influence Contemporary India-I, NCERT Class IX, Climate, p.37.

When analyzing a city's profile, we look at the Annual Range of Temperature (the difference between the hottest and coldest months). In the tropical south and along the coasts, this range is remarkably low—often between 3°C to 6°C—because of the proximity to the equator and the sea Geography of India, Majid Husain, Climate of India, p.37. As you move north into the Upper Ganga Plains or the Thar Desert, this range expands significantly. For instance, while Mumbai stays humid and warm, Delhi can see temperatures soar to 40°C in May and dip below 8°C in January, creating a massive annual swing Fundamentals of Physical Geography, NCERT Class XI, Solar Radiation, p.75.

City Type	Example	Temp. Range	Key Characteristic
Coastal / Peninsular	Mumbai, Chennai	Low (3–9°C)	High humidity; moderate temperatures year-round.
Inland / Continental	Delhi, Nagpur	High (15–20°C+)	Extreme summers; distinct winter season.
High Altitude	Leh, Shimla	Variable	Very low mean annual temperatures; low oxygen.

Rainfall further refines these profiles. A city like Shillong is defined by its massive rainfall (over 1400 cm), whereas Jodhpur is defined by its aridity Contemporary India-I, NCERT Class IX, Climate, p.37. Interestingly, even among coastal cities, timing varies: Mumbai gets slammed by the South-West Monsoon in June-July, while Chennai receives a significant portion of its rain later in the year during the retreating monsoon phase.

Sources: Contemporary India-I, NCERT Class IX, Climate, p.37; Geography of India, Majid Husain, Climate of India, p.37; Fundamentals of Physical Geography, NCERT Class XI, Solar Radiation, Heat Balance and Temperature, p.75

7. Solving the Original PYQ (exam-level)

This question is a classic application of the Continentality vs. Maritime effect and Rainfall Distribution concepts you just mastered. The most critical clue here is the low annual range of temperature (9°C). This small variation between the hottest and coldest months tells us the station must be near the coast, where the sea’s moderating influence prevents the extreme temperature swings found in the interior. When you combine this with a high average annual temperature of 26°C, you are looking for a tropical peninsular station that remains warm year-round without being subject to the harsh winters of the north.

To arrive at the correct answer, Chennai, we must use the process of elimination based on the 63 cm rainfall figure. While Chennai is famous for its North-East Monsoon, its total annual rainfall is significantly lower than the heavy monsoon regimes of the East. Reasoning through the options: Cherrapunji is an obvious trap; it is one of the wettest places on Earth with rainfall exceeding 1,000 cm, making 63 cm impossible. Similarly, Kolkata sits in a humid deltaic region with rainfall typically well above 150 cm. Allahabad, being deep in the Gangetic Plain, exhibits a continental climate with a much higher annual temperature range (often exceeding 15-20°C) and higher rainfall than the station described.

UPSC often uses these "Climate Data" questions to test your ability to prioritize constraints. The 9°C temperature range is the "hard" constraint that eliminates inland cities like Allahabad, while the moderate rainfall eliminates the high-precipitation zones of the Northeast and the Delta. As noted in Geography of India by Majid Husain, stations in the semi-arid subtropical or drier peninsular zones often reflect these specific moderate rainfall and low-range characteristics, making (B) Chennai the only scientifically consistent choice.