Why Do Cyclones Occur Only in Winter? The Science Behind Cyclones and Cold Weather
Cyclones, or tropical cyclones, are powerful storms that form over warm ocean waters, bringing heavy rain, high winds, and sometimes devastation. In India, they often strike during the post-monsoon months of October to December, coinciding with the onset of winter. This timing raises a common question: why do cyclones happen primarily in winter, and what’s the connection between these storms and cold weather? The short answer is that cyclones don't "occur only in winter" due to cold temperatures alone—they're driven by warm sea surfaces persisting into cooler months, creating ideal atmospheric instability. Based on meteorological insights, here's a clear explanation, including recent examples like Cyclone Montha.
The Science of Cyclone Formation
Cyclones require specific conditions to develop:
Warm Sea Surface Temperatures: At least 26°C is essential, as it evaporates water into moist air that rises, forming low-pressure areas. This rising air cools and condenses, releasing heat that fuels the storm's rotation.
Atmospheric Instability: Cool air above the warm ocean creates a temperature contrast, promoting upward air movement. Strong winds and high humidity then organize the system into a cyclone.
Coriolis Effect: Earth's rotation adds the spin, typically in tropical latitudes (5-20 degrees from the equator).
In summer (June-September), the monsoon dominates, suppressing cyclone formation with widespread rain and stable air. Winter's cooler upper atmosphere contrasts with lingering warm seas (from summer heat), sparking the instability needed for cyclones. This "winter" pattern (post-monsoon) peaks in October-December for the Bay of Bengal and Arabian Sea.
Connection Between Cyclones and Cold Weather
Cold weather isn't the direct cause—it's the contrast between warm oceans and cooler air aloft that triggers cyclones. In winter:
Sea temperatures remain above 26°C (retained from summer), providing energy.
Upper air cools (due to seasonal shifts), creating instability for low-pressure systems to form and intensify.
Reduced wind shear (less disruption) allows storms to organize.
This dynamic is why cyclones are more frequent in cooler months globally (e.g., Atlantic hurricanes in late summer-fall). In India, the Bay of Bengal sees 5-6 cyclones annually, mostly October-December, while the Arabian Sea has 1-2, often in May-June or November.
Recent Example: Cyclone Montha
As of October 27, 2025, a deep low-pressure area in the southeastern Bay of Bengal is intensifying into Cyclone Montha, expected to hit West Bengal and Tamil Nadu between October 28-31. An orange alert is issued for heavy rainfall and winds up to 60 km/h, with fishermen warned to stay ashore. The Indian Army is on standby. This post-monsoon storm exemplifies winter cyclone risks, driven by warm seas and cooling air.
Key Takeaways for India
Risk Zones: East Coast (Bay of Bengal) sees more cyclones; West Coast (Arabian Sea) fewer but intense.
Climate Change Impact: Warmer oceans may increase frequency and strength—2025 has already seen above-average activity.
Preparation Tips: Evacuate low-lying areas, stock essentials, and follow IMD alerts (imd.gov.in).
Cyclones in winter are nature’s reminder of ocean-atmosphere dance—warm below, cool above. Stay safe, bhai!
What’s the Hype on Cyclones in Winter?
Why winter?
Warm seas (26°C+) persist, contrasting cooler upper air for instability.
Cold connection?
Cool air aloft fuels low-pressure rise; not direct cold cause.
Recent example?
Cyclone Montha (Oct 2025) hitting West Bengal/Tamil Nadu.
India risks?
Bay of Bengal: 5-6 yearly (Oct-Dec); Arabian Sea: 1-2.
Prep tip?
Check IMD alerts; evacuate low areas during warnings.
