Excess deaths can be defined as the difference between the actual number of deaths in a particular period and the estimated number of deaths expected in that period. Expected deaths can be derived in a variety of ways for different purposes, which means that there may be different estimates of excess deaths published by different organisations and used for those specific purposes. Excess deaths attributable to specific factors – such as hot or cold temperature – can also be estimated by using a statistical model of the relationship between the factor and the number of deaths.

This document explains the major publications related to excess deaths in the UK. Details of the methodologies are published by individual organisations.

The Office for National Statistics (ONS) is responsible for collecting, analysing and disseminating statistics about the UK’s economy, society and population. As such, ONS produces statistics related to the registration of life events which includes publication of Deaths registered weekly in England and Wales. National Records of Scotland (NRS) and Northern Ireland Statistics and Research Agency (NISRA) are responsible for mortality outputs for Scotland and Northern Ireland, respectively.

The Office for Health Improvement and Disparities (OHID) forms part of the Department of Health and Social Care (DHSC) and is responsible for work to improve the nation’s health and reduce health disparities. OHID produces the monthly publication Excess mortality in England.

The UK Health Security Agency (UKHSA) is responsible for surveillance of infectious diseases and other health related threats to the security of the nation’s health. UKHSA currently produces 3 excess mortality related products: [Weekly all-cause mortality surveillance in England](Weekly all-cause mortality surveillance: 2024 to 2025 - GOV.UK, Annual heat mortality monitoring in England and Annual surveillance of influenza and other seasonal respiratory viruses in the UK.

The majority of deaths are not registered on the day they occurred (more details are available here). Some of the publications listed in this explainer count the number of deaths by the date the death was registered, and some count the number of deaths by the actual date when the death occurred . Publications which use the date of registration avoid uncertainty about deaths that have occurred and not been registered yet, but are less precise about the timing of deaths (for instance a death which occurred on a Saturday would not be registered until the following Monday at the earliest, and usually later). Publications which use the date of death occurrence allow more precise attribution of potential causes of changes in mortality rates over time, but usually have only partially complete data due to the delays in registration of deaths.   

This publication contains the headline figures on death registrations and excess deaths for England and is the most appropriate for making comparisons across each of the devolved administrations of the UK. The publication also includes numbers of death registrations and excess deaths for each of the 4 UK countries as well as the UK as a whole. The statistics are broken down by age and sex.

On 20 February 2024, ONS published a new method for measuring excess mortality.

ONS’s methodology is closely aligned with OHID’s methodology described below. Both organisations publish estimates of excess deaths for England. Those produced by ONS are consistent with estimates for other UK countries. However, OHID’s methodology can be disaggregated by local authorities within England, whereas ONS’s permits only regional breakdowns in England.

This publication is the most appropriate to use when comparing excess mortality within England. The publication provides estimated numbers of excess deaths and the ratio of registered to expected deaths. Users can adjust the time periods presented, allowing cumulative estimates to be shown for specific periods. OHID produces breakdowns which show inequalities in levels of excess mortality, including by sex, age group and level of deprivation for the English regions and local authorities. OHID’s analysis by cause of death describes which causes are particularly contributing to excess deaths in specific time periods.

OHID first published this revised version of its report on 20 February 2024. This new analysis and methodology is aligned with ONS’s method where possible. These estimates represent the number of deaths above the number expected, based on trends in mortality over the previous 5 years.

All-cause mortality surveillance shows time periods when mortality levels were higher than expected, rather than providing an estimate of the number of actual or expected deaths. The weekly all-cause mortality surveillance reports are published every Thursday.

This publication includes details of the weeks in which observed deaths were higher than an expected threshold, which is calculated using a European-wide algorithm called Euromomo. It includes a chart of observed and expected deaths by the date the death occurred across all ages in England. The chart also shows the upper limit for when the number of deaths is considered to be significantly higher than expected.

This publication can be used for making international comparisons and for other surveillance purposes, prompting further investigation to determining the cause, and assessing the impact of known health events. Health events could include high levels of influenza, extreme heat or extreme cold, for example.

The surveillance of influenza and other seasonal respiratory viruses in the UK statistics are published every year after the winter period.

This publication includes estimates of the number of deaths attributable to influenza, COVID-19 and extreme cold using all-cause mortality data.

This publication can be used to indicate the potential mortality burden from COVID-19, other respiratory diseases and extreme cold.

The report uses an adapted version of the FluMOMO model, which was developed to incorporate COVID-19, details of which are given in the 2023 working paper.

UKHSA estimates the number of deaths associated with heat in each summer. Heat episodes are defined as periods in which an amber Heat-Health Alert (HHA) is issued in at least one region, or the mean central England temperature is at least 20°C. Deaths during heat episodes are compared with deaths in a baseline period (the 14 days before and 14 days after a heat episode) to estimate heat-associated mortality. Years of life lost are also calculated, as a measure of premature mortality. The data on deaths is stratified by heat episode, region and age group. Since 2023, a breakdown by sex has been included. In 2024, further breakdowns by local resilience forum area, place of death and cause of death were added.

Additionally, in the 2022 report onwards the publication provides a comparison between observed deaths and modelled estimates. The modelled estimates are derived by applying a statistical model of the temperature-mortality relationship in England in the previous 5 years to the temperatures observed in that summer. This allows identification of heat episodes where heat-associated deaths were higher or lower than would be expected for those temperatures.

UKHSA’s heat mortality monitoring provides information on excess deaths observed during episodes of heat each year (known as heat-associated deaths) to inform public health actions and the continuous improvement of the Weather-Health Alerting system in England. It provides information on the observed impacts of heat on health, and how these impacts vary depending on temperature and other factors. The publication can be used to understand trends in the number of heat episode days and heat-associated deaths over time. It forms part of monitoring progress against the goals of the Adverse Weather and Health Plan for England to reduce mortality and premature mortality related to adverse weather.

The publication compares the relative risk of death associated with a range of temperatures, including both cold and heat, with breakdowns for English regions and demographic characteristics.

The ONS has worked in collaboration with partners at the London School of Hygiene and Tropical Medicine, the Department of Health and Social Care (DHSC) and Wellcome to develop this method, that adopts techniques used widely in climate research globally. These are Official Statistics in Development. The methods are under development, which means estimates may change.

The ONS publication includes attributable deaths associated with heat and cold. These estimates represent a modelled estimate of excess deaths associated with hotter and colder days, based on temperatures experienced across different locations, while adjusting for other factors influencing mortality. This method uses daily deaths and daily temperatures occurring over 35 years to model the association between outdoor temperature (both heat and cold) and mortality. It adjusts for seasonal and long-term trends, as well as other factors influencing mortality trends, such as air pollution, and was developed based on global scientific research which focuses on the impacts of climate change. This approach provides insight into the impact of a range of temperatures, incorporating delayed effects because studies have shown that temperature-related deaths can occur some time after the exposure to hot or cold weather.

Published 20 February 2024

Last updated 2 July 2025 show all updates