Why Do More People Die in Winter?

England’s Seasonal Mortality Pattern Explained. Based on ONS daily all-cause mortality data, England, 2014–2023

Every year, without fail, the same pattern emerges in England’s mortality statistics. As the days shorten and temperatures drop, the number of people dying each day climbs steadily upward, peaking in the bleak heart of January, before easing back as spring arrives. This is not a new discovery, nor a statistical curiosity. It is one of the most consistent and consequential patterns in public health, and understanding it is vital if we are serious about protecting the most vulnerable members of our society.

Using daily all-cause mortality data from the Office for National Statistics (ONS), covering over 3,200 days between June 2014 and May 2023, we can trace this seasonal rhythm with striking clarity.

The Scale of the Problem

The headline number is stark: on average, roughly 1,600 people die each day in England during the winter months (December through February), compared to around 1,235 during the summer (June through August). That is a difference of nearly 30%, or approximately 365 additional deaths per day in winter. Scaled over the three-month winter period, this translates to somewhere in the region of 30,000 to 35,000 excess deaths compared to what we might expect if mortality rates stayed at summer levels.

January is consistently the deadliest month of the year, averaging around 1,670 deaths per day across the study period. August, by contrast, is typically the safest. Some individual winter days, particularly during severe influenza seasons, have seen totals exceed 2,000.

Figure 1. Daily all-cause deaths (grey) with 7-day rolling average (blue). Winter periods (December–February) are shaded in blue; the COVID-19 period in red. England, June 2014–May 2023.

The first figure makes the seasonal structure impossible to miss. Each year, as we enter winter, the rolling average rises sharply — forming a distinctive spike before retreating in spring. The 2017–18 winter stands out even before the pandemic, with January and February 2018 recording a daily average close to 1,730 deaths, driven by a severe influenza A (H3N2) season which hit older people particularly hard.

Then comes the unmistakable rupture of spring 2020. The COVID-19 pandemic produced a mortality spike entirely unlike anything in the preceding six years — reaching a peak of 3,097 deaths in a single day on 8 April 2020. While this dwarfs any winter peak in the series, the virus repeatedly resurged during autumn and winter months in subsequent years, reinforcing the seasonal pattern even under pandemic conditions.

Why Does Winter Kill?

The causes of excess winter mortality are multiple and interlocking. No single factor can fully explain it, which is also why it has proved so difficult to eliminate.

Respiratory infections are the dominant driver. Influenza and, more recently, SARS-CoV-2 thrive in the cold, dry air of winter and in the enclosed indoor settings where people congregate when they cannot be outside. Respiratory syncytial virus (RSV) adds to the burden, particularly among older adults and young children. Cold air itself can directly irritate the airways, triggering acute exacerbations in those with asthma or chronic obstructive pulmonary disease (COPD).

Cardiovascular disease accounts for a large share of excess winter deaths. Cold temperatures trigger physiological responses, vasoconstriction, increased blood viscosity, elevated blood pressure, that raise the risk of heart attacks and strokes. Studies have found that the risk of myocardial infarction rises significantly when outdoor temperatures fall, even after accounting for other factors.

Cold homes amplify these risks considerably. England has some of the least thermally efficient housing stock in Western Europe, and many households, particularly older people on fixed incomes,  live in conditions that are chronically under-heated. Fuel poverty intersects with vulnerability in painful ways: those least able to afford adequate heating are often those whose health suffers most acutely from the cold.

Age and frailty compound everything. The very old are disproportionately represented in winter mortality statistics. Their immune responses are less robust, their thermoregulatory capacity is reduced, and many live with multiple chronic conditions that act as tinder when the cold ignites an infection or cardiovascular event. Social isolation in winter, when mobility is limited and social contact drops, can further delay help-seeking and accelerate deterioration.

The Seasonal Mortality Profile

Figure 2. Average deaths by day of year for typical years (2014–19 and 2022–23, blue) versus COVID years (2020–21, dashed red). Winter months (December–February) are shaded. England.

The second figure strips away the year-by-year noise to reveal the underlying seasonal shape. The deep trough of summer, running from roughly June through September, gives way to a steady climb from October, a sharp peak in January, and then a gradual descent through spring.

Two features are worth highlighting. First, the pattern is remarkably consistent across normal years: this is not a quirk of one bad season, but a structural feature of mortality in England. Second, the COVID years of 2020–21 show a dramatically elevated profile across much of the year, with a spring peak in 2020 that distorts the usual shape — but even in those years, the underlying winter amplification remains visible.

What Is Killing People in Winter?

Beyond the aggregate figures, ONS excess winter deaths bulletins allow us to examine which conditions are actually responsible for the seasonal surge. Figure 3 shows the share of excess winter deaths attributable to each major cause group across selected winters from 2014/15 to 2021/22.

Figure 3. Share of excess winter deaths by cause group, England, selected winters 2014/15–2021/22. Respiratory includes influenza, pneumonia and COPD. Source: ONS Winter Mortality bulletins.

Respiratory disease is consistently the single largest contributor, accounting for between 34% and 44% of all excess winter deaths across the years shown. Dementia and Alzheimer’s disease, a perhaps surprising second, accounts for around a fifth of excess winter deaths in most years, reflecting how cold temperatures and infection combine lethally in people with advanced cognitive decline. Circulatory disease (heart attacks and strokes) contributes a further 14–21%. Together, these three cause groups account for roughly three-quarters of all excess winter deaths — a finding with clear implications for where prevention efforts should be focused.

One feature of Figure 3 invites closer attention: the respiratory share in 2021/22 appears lower than in preceding winters. This is not simply a biological anomaly but the result of two overlapping effects. First, pandemic control measures, mask-wearing, social distancing, reduced indoor mixing, genuinely suppressed influenza and other respiratory viruses during this period, with research suggesting mask-wearing alone reduced influenza activity by 11–35% in England. Second, and perhaps more importantly, there is a classification effect at work: many deaths that would in earlier years have been coded as respiratory in origin, pneumonia, respiratory failure, were instead registered under COVID-19 as a distinct cause of death. The respiratory slice of the chart therefore looks artificially deflated, not because fewer people died of breathing-related causes, but because many of those deaths were recorded under a different label.

Are We Making Progress?

The picture is mixed. Influenza vaccination campaigns have grown in scale and scope, and there is clear evidence that they reduce mortality in older age groups. The introduction of COVID-19 vaccines from late 2020 onwards has prevented large numbers of deaths. Housing energy efficiency programmes have made some inroads, though the scale of England’s cold-homes problem remains vast.

Yet excess winter mortality has not disappeared. Part of the reason is that the gap between England and countries with colder climates, such as Sweden or Finland, remains puzzling. Scandinavian nations, despite far harsher winters, tend to have lower excess winter mortality than England. The difference lies largely in housing standards and cultural habits around outdoor activity in cold weather, rather than temperature alone. This points to a fundamentally preventable element in England’s winter death toll.

What Could Change?

Eliminating excess winter mortality entirely is probably not achievable — some seasonal variation is biological reality. But the current scale of winter deaths in England reflects policy choices as much as meteorology. Improving the energy efficiency of homes, expanding access to winter vaccines, strengthening social care for isolated older people, and ensuring that cold-weather health advice reaches those who need it most could all contribute to meaningful reductions.

Thirty thousand extra deaths every winter is not an act of nature we are powerless to prevent. It is a challenge we already know how to address, at least in part. The data is there, laid out in every dip and spike of the mortality curve. The question is whether we treat it with the urgency it deserves.

Data:

• ONS, Daily deaths by date of occurrence, England, June 2014–May 2023; ONS Winter Mortality bulletins 2014/15–2021/22. Excess winter deaths estimates for Figure 3 exclude COVID years (2020/21). Respiratory suppression evidence: UKHSA Influenza Surveillance Reports 2021–22; published research on non-pharmaceutical interventions and influenza transmission.