A Cardiologist’s Perspective

Following an extremely hot summer and a heavy, widespread monsoon season that triggered devastating floods across parts of North India, the attention of meteorologists, public health officials, and millions of citizens now turn to the forthcoming winter. The intensity of the preceding seasons is not a mere memory; it is a critical variable that will likely influence the severity of the coming cold, with profound and predictable consequences, particularly for cardiovascular health.

Climatological models for South Asia, especially concerning the Indian subcontinent, suggest a heightened probability of a colder-than-average winter, particularly across the northern, central, and eastern regions. This prediction is bolstered by the potential development of a La Niña event in the equatorial Pacific, which is the cooler counterpart to El Niño. Historically, La Niña conditions have been correlated with harsher, colder winters in India, intensifying cold wave durations and increasing the likelihood of above-normal snowfall in the Himalayan regions.

The preceding extreme seasons also play a subtle but significant role. A sustained, heavy monsoon, like the one that led to widespread flooding in North India, injects a vast amount of moisture into the soil and atmosphere. This increased soil moisture and atmospheric humidity can lead to an amplified cooling effect once the monsoonal winds retreat and the cold, dry air masses from the north (Northeast Monsoon) begin to dominate. When combined with the already predictable influence of a La Niña phase, this creates a fertile ground for a more potent winter. Regarding the prediction for the Kashmir Valley winter reports remain unconfirmed, regional meteorological departments will release detailed and reliable forecasts closer to the onset of the traditional winter season, particularly with the start of the ‘Chillai Kalan’ period.

A severe winter means intensified cold waves in the Northern and central regions, including the densely populated Indo-Gangetic Plains which are likely to face prolonged periods of biting cold, with minimum temperatures dropping significantly below the seasonal average. The peak cold period of December to February may begin earlier and linger longer, extending the window of cold-related stress. With colder temperatures, combined with a dip in the boundary layer height and persistent post-monsoon haze or dust, will likely trap pollutants, leading to a spike in winter air pollution—a critical concern for urban centres like Delhi-NCR. Air quality is highly likely to significantly deteriorate in many parts of India, particularly in the North, following Dussehra and Diwali. The combination of firework emissions during the festivals, the onset of winter meteorological conditions (lower wind speed, reduced vertical mixing, and lower temperatures leading to the trapping of pollutants), and regional sources like stubble burning in North India’s agricultural belt creates a perfect storm for severe smog. Fine Particulate Matter (PM2.5​) is the primary concern, as its tiny size allows it to penetrate deep into the lungs and enter the bloodstream.

Effects on cardio-vascular health: The human body’s response to cold temperatures is a well-documented physiological mechanism that puts significant strain on the cardiovascular system. Past experiences across India and other parts of the world consistently show a marked seasonal increase in cardiovascular-related morbidity and mortality during the winter months. This increase is not random; it is a predictable public health crisis rooted in physiological and environmental factors. The body attempts to conserve core heat by constricting peripheral blood vessels. This involuntary response significantly increases systemic vascular resistance, leading to a rise in blood pressure. For individuals with pre-existing hypertension or coronary artery disease, this sudden and sustained elevation dramatically increases the risk of a hypertensive crisis, stroke, or a heart attack (Myocardial Infarction).

Cold exposure is associated with changes in blood composition, including increased platelet count and viscosity. Thicker blood is more prone to clot formation (thrombogenesis), directly elevating the risk of acute coronary syndromes and ischemic stroke. This coupled with the fact that the heart has to pump harder against the elevated blood pressure and through the more viscous blood, increasing its overall workload and oxygen demand.

The preceding extreme summer and monsoon exacerbate this risk in two critical ways: The heavy monsoon and subsequent floods in North India likely left a large population group—particularly the socio-economically vulnerable—with compromised health. Water-borne and vector-borne diseases spike during and immediately after floods, and the associated systemic infections, such as flu and pneumonia, trigger significant inflammatory responses. This systemic inflammation is a powerful precursor to cardiovascular events, even weeks or months later. Individuals who endured the heat and recovered from monsoon-related illnesses will enter the winter with an already stressed, pro-inflammatory cardiovascular profile, making them exceptionally susceptible to the cold’s effects. The intensification of the smog and exposure to fine particulate matter (PM2.5​) is strongly linked to inflammation, oxidative stress, and the rupture of atherosclerotic plaques. For the heart, the combined effect of cold-induced vasoconstriction and pollution-induced inflammation creates a synergistic, highly dangerous environment. This combination will predictably drive-up hospital admissions for heart failure, arrhythmias, and acute myocardial infarction.

Policymakers and the medical community must prepare for a surge in heart attacks, strokes and exacerbation of chronic heart failure.  Proactive public health measures—including community weather warning systems, dedicated winter clinics, and targeted awareness campaigns promoting warmth, indoor activity, and strict management of hypertension and diabetes—will be essential to mitigate the predictable and a serious cardiological fallout of a severe winter. The time for preparation is now, before it becomes too late. “An ounce of prevention is better than a pound of cure”.

Prof Upendra Kaul, Founder Director Gauri Kaul Foundation