Climate of Rajasthan
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Rajasthan experiences an extreme arid to semi-arid climate — from the scorching hot desert of the west to the relatively moderate climate of the Aravalli-forested eastern region. The climate is governed primarily by its location in the northwestern part of India, far from maritime influences.
Key Facts for RPSC RAS:
- Rajasthan receives highly skewed rainfall — the western desert receives less than 100mm annually, while Mount Abu receives over 1,500mm.
- The monsoon arrives in Rajasthan in July — delayed by approximately 2-3 weeks compared to Kerala.
- The Aravalli range acts as a barrier, creating a significant rain shadow to its west.
- Summer temperatures in Jaisalmer and Bikaner can exceed 49°C (May-June).
- Winter temperatures in the same areas drop to below 0°C in January — extreme continental climate.
- The Indira Gandhi Canal has moderated the microclimate of western Rajasthan significantly.
⚡ Exam tip: The distribution of rainfall across Rajasthan — contrasting the western arid zone with the southeastern humid zone — is a high-yield topic. Know the names and districts of the four rainfall zones.
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General Climate Characteristics
Rajasthan exhibits extreme continentality — it experiences some of the most severe temperature ranges in India:
- Summer (April-June): Extremely hot, especially in the west — temperatures frequently exceed 45°C, with Jaisalmer and Bikaner recording over 49°C.
- Monsoon (July-September): Humid but brief, with the state receiving 90% of its annual rainfall.
- Post-Monsoon (October-November): Pleasant, with clear skies and mild temperatures.
- Winter (December-February): Cold and dry, with temperatures dropping to near freezing in the west.
Factors Influencing Rajasthan’s Climate
1. Latitude: Located between approximately 24°N to 30°N — within the tropical zone, but the absence of maritime influence makes it continental.
2. Continentality: Being far from the sea (landlocked state), Rajasthan lacks the moderating influence of ocean temperatures. This causes:
- Very hot summers
- Cold winters
- Low humidity throughout the year
- Large diurnal temperature ranges (day-night temperature differences of 15-20°C)
3. Aravalli Range: The northwest-southeast trending Aravalli hills:
- Block moisture-laden southwest monsoon winds from the Arabian Sea
- Create a pronounced rain shadow effect in western Rajasthan
- Eastern Rajasthan receives more rainfall due to orographic uplift
4. Western Disturbances: During winter, Western Disturbances (extra-tropical storms from the Mediterranean) bring light rain and cold winds to northern Rajasthan, influencing the winter climate significantly.
5. Thar Desert: The sand of the Thar Desert:
- Heats up rapidly during the day → intense daytime heating
- Cools rapidly at night → extreme night cooling
- Creates local thermal low-pressure systems in summer that attract monsoon winds
Rainfall Distribution
Rajasthan is divided into four distinct rainfall zones:
| Zone | Annual Rainfall | Districts Covered |
|---|---|---|
| Arid Zone | < 100mm | Jaisalmer, Barmer (western Thar) |
| Hyper-arid Zone | 100-200mm | Bikaner, Jodhpur, Nagaur |
| Semi-arid Zone | 200-400mm | Jaipur, Ajmer, Sikar, Jhunjhunu |
| Sub-humid Zone | 400-900mm | Kota, Bundi, Jhalawar, parts of Udaipur |
| Humid Zone | > 900mm | Mount Abu (Sirohi), parts of Udaipur, Rajsamand |
Note: Some classifications use only three or four zones, with Mount Abu’s zone (>1,500mm) often classified separately as the wet humid zone.
The Monsoon Mechanism
The Southwest Monsoon arrives in Rajasthan through two branches:
1. Arabian Sea Branch:
- Enters Rajasthan from the Gujarat coast
- Moves north-northwest through the Aravalli corridor
- Brings rainfall to southeastern Rajasthan (Kota, Jhalawar) and the eastern slopes of the Aravallis
- The Aravalli corridor between the hills of Udaipur and the sandy plains allows this moisture to penetrate further west
2. Bay of Bengal Branch:
- Enters Rajasthan from the east via the Yamuna-Ganga plain
- Brings moisture that has crossed central India
- Influences the eastern districts (Kota, Bundi, Bharatpur)
The Aravalli’s Rain Shadow Effect: The Aravalli range (trending NW-SE) blocks the southwest monsoon effectively:
- Eastern Aravalli slopes: Receive more rainfall — Jaipur, Sawai Madhopur, Kota
- Western side (Aravalli to Thar): Extremely dry — Jaisalmer, Barmer, Bikaner
This creates one of the world’s most dramatic climatic gradients — within 400 km, rainfall drops from 600mm+ to under 100mm.
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Detailed Climate Analysis
Seasonal Temperature Patterns
Summer (March to June):
- March-April: Rapid warming begins; temperatures reach 35-40°C
- May-June: Peak summer — Bikaner, Jaisalmer, Jodhpur regularly exceed 48°C
- The highest recorded temperature in Rajasthan is 50.6°C at Jaisalmer (June 2020)
- The sand dunes heat up to 70-80°C during peak afternoon
- Loo winds — hot, dry winds from the west (Pakistan/Rajasthan border) — are characteristic of May-June
Winter (December to February):
- Nights are extremely cold in the desert — Jaisalmer and Bikaner can drop to -2°C to -3°C
- Frost formation is common in the sandy plains during December-January
- Day temperatures are pleasant (20-25°C), creating a large diurnal range
- Western disturbances bring cloud cover and occasional rain to northern districts
Diurnal Temperature Range: Rajasthan has one of the highest diurnal temperature ranges in the world during winter — daytime may be 25°C while night temperatures drop to -2°C, a range of 27°C.
Drought and Desertification
Rajasthan is highly prone to drought, experiencing severe drought conditions every 3-5 years:
Drought classification:
- ** Meteorological drought:** When rainfall is below 75% of normal
- ** Agricultural drought:** When soil moisture is insufficient for crops
- Hydrological drought: When groundwater and reservoir levels decline
Major drought years: 1918, 1939, 1968, 1985, 2002, 2009, 2012 (partial), 2022 (severe)
Desertification in Rajasthan:
- Wind erosion is the primary driver of desertification — the Thar Desert is expanding eastward
- Water erosion affects the Aravalli slopes
- Salinisation of soil is a growing problem in canal-irrigated areas (e.g., Bikaner, Ganganagar)
- The Indira Gandhi Canal has brought both irrigation and soil salinity challenges
Wind Patterns and the Loo
Loo winds are the characteristic hot, dry winds of summer in Rajasthan:
- Originate in the Iranian-Baluch desert region
- Blow across western Rajasthan during May-June
- Cause heat strokes and respiratory problems
- Temperature often 8-10°C above normal during Loo episodes
- Come from the west/northwest direction
Sandstorms are common in the Thar during pre-monsoon months (April-June):
- Caused by strong convective activity over the heated desert floor
- Can reduce visibility to less than 100 metres
- Often precede the monsoon onset
Cloudbursts and Flash Floods
While Rajasthan is predominantly dry, the south-eastern districts (Kota, Jhalawar, Bundi) experience cloudbursts during the monsoon:
- Occur when moisture-laden monsoon winds hit the Vindhyan hills
- Can bring 200-300mm of rain in a single day
- Cause devastating flash floods in the Chambal and Banas basins
- The 2010 floods in Kota caused massive destruction — over 100 deaths
Climate Classification (Koeppen)
| Zone | Koeppen Type | Characteristics |
|---|---|---|
| Western Thar (Jaisalmer, Barmer) | BWhw | Hot desert, winter rainfall |
| Eastern Plains (Jaipur, Ajmer) | BShw | Hot semi-arid |
| Aravalli Hills (Udaipur region) | BSh | Semi-arid, subtropical |
| Kota-Bundi region | Cg | Humid subtropical |
| Mount Abu | Cfb | Temperate oceanic |
Note: BWhw = Hot desert climate (BWh) with winter rainfall (w). Cg = Subtropical with dry winter.
The Impact of Climate on Agriculture
- Arid zone farming: Dependent on drip irrigation and drought-resistant crops (bajra, moong)
- Semi-arid zone: Mixed farming with some canal irrigation
- Monsoon-dependency: 70% of Rajasthan’s agriculture is rain-fed (unirrigated)
- The monsoon failure is the single largest cause of farmer distress in Rajasthan, more than any other factor
The Indira Gandhi Canal and Climate Modification
The Indira Gandhi Canal (originally Rajasthan Canal) — India’s largest canal — has significantly altered the microclimate of western Rajasthan:
- Has transformed lakebeds and sand dunes into agricultural fields
- Has increased humidity in the surrounding area
- Has supported afforestation in the desert margins (e.g., Jaisalmer’s Golden City forest project)
- The greening effect has reduced dust storms and moderated temperatures
Practice Questions for RPSC RAS
- How does the Aravalli range influence the rainfall pattern of Rajasthan? Explain with reference to the rain shadow effect.
- Distinguish between arid and semi-arid climate zones of Rajasthan. Give district examples and characteristic vegetation.
- What are Loo winds? How do they affect the climate and people of Rajasthan?
- Why does Rajasthan experience extreme diurnal temperature variation? What is its impact on agriculture?
- Analyse the impact of Western Disturbances on Rajasthan’s winter climate.
Common Mistakes to Avoid
- Thinking all of Rajasthan is desert — southeastern Rajasthan (Kota, Jhalawar) is actually quite humid and forested.
- Confusing the monsoon arrival dates — Rajasthan receives monsoon about 3-4 weeks after Kerala; it does not start in June but in early July.
- Forgetting the role of western disturbances — these are critical for winter rainfall in northern Rajasthan and are often missed.
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