How deadly was this year’s heatwave?

This report is from the Office of National Statistics:

Weeks of relentless warm weather have triggered reports of a spike in heat-related deaths, with some claiming the heatwave has now cost hundreds of lives. As Nick Stripe explains, those claims are not supported by the published data – but a summer spike in heat-related deaths can’t be ruled out yet. What’s not in dispute is that week after week of almost relentless sunshine are making this one of the warmest and driest British summer in years. This has led to media reports that the heat has already taken hundreds of lives with grim warnings that the toll “could reach thousands.”

The stories are based on provisional ONS weekly deaths figures which show 995 more deaths than the five-year average were registered in England and Wales during the seven weeks from 2^nd June to 20^th July.  However, it is impossible to tell from the data currently available to us how many people actually died during this period and how many of those deaths were as a result of the heat.  The provisional weekly deaths figures we release are based on the date the deaths were registered – not the date each person died.

Later in the year we will be able to produce accurate figures by exact day of death which can be related to temperature if necessary.  While most deaths should be registered within five days, they can be delayed by months if they are referred to a coroner. This means the figure of 995 will include people who died before the hot weather, while potentially leaving out others who did die during the recent heatwave.

Although the provisional data currently available appear to show a high number, it’s not really clear how meaningful this is.  Despite an ageing and growing population, fewer deaths were registered during this seven-week period than during the same weeks of the last two years – at 65,439 in 2018 compared to 65,846 in 2017 and 65,728 in 2016.

And although this was 995 more registrations than the rolling five-year average for this period, there were more than twice as many registrations above the rolling average in 2017 (2,332), and more than three times as many in both 2016 (3,099) and 2015 (3,516).