People enjoy the sun and heat but it is perhaps easy to be lulled into a false sense of security during this weather.
More action is needed to help protect people against the health impacts of hot weather outside extreme heatwaves, a study has urged.
Most excess deaths and hospital emissions in hot summer conditions occur outside severe heatwaves, the report led by the London School of Hygiene and Tropical Medicine found.
And most people do not consider themselves to be at risk from hot weather, which is on the rise as the climate changes, the assessment shows.
The study looked at the impact of the heatwave plan for England, brought in after the 2003 heatwave which caused 2,000 excess deaths in the UK.
The plan aims to protect health in the face of heatwaves, with guidance for the general public, local authorities, the NHS, social care and other agencies, underpinned by an alert system triggered by extreme temperatures in the summer.
But the analysis found that most deaths and hospital admissions associated with heat happen outside periods when the alert system is triggered.
Some 95% of heat-related deaths in London and the West Midlands occurred in hot weather below the heatwave action threshold, which in the capital is 32C (89.6F) in the daytime.
It also revealed that frontline nurses reported they often struggled to protect patients during heatwaves, often in old and poorly designed buildings not well adapted for climate change and with a lack of funding and resources.
Local weather variations - for example cooler conditions by the seaside - led some local authorities to ignore regional alerts and potentially underestimate the threat of hot weather as they do not experience temperatures that hit the alert threshold.
Local heatwave plans are aligned with the national scheme, but spells of very hot weather were often assessed as lower risk than other extremes such as floods and cold snaps and given a lower priority in planning.
More preparation is needed to reduce the risks of damage to health when temperatures are below the heat-health alert thresholds, with a focus on the summer season as a whole rather than heatwaves alone, experts said.
And more public awareness of the dangers is needed, the study found, as most adults in England do not consider themselves at risk - even those in "vulnerable" groups, with certain health conditions or aged 75 and over.
Most people, particularly those under 45, tend to have positive views of hot weather.
The public mostly recognise some actions to protect from hot weather, such as cool drinks and staying out of the sun between 11am and 3pm.
But they do not know about other effective measures such as keeping windows and curtains closed where they are exposed to the sun, and avoiding alcohol.
Professor Nicholas Mays said: "The results from this study highlight the importance of ensuring that health and social services are prepared to protect those who are most at risk as average summer temperatures rise.
"People especially vulnerable to hot weather include older people over age 75, and people with certain health conditions.
"Some of the most vulnerable can also be hard to reach, such as the homeless community, and need additional consideration.
"People enjoy the sun and heat but it is perhaps easy to be lulled into a false sense of security during this weather."
He said the heatwave plan appeared to have helped reduce health impacts above the extreme heat threshold, but the approach needed to be altered to reflect risks to health that occur outside those periods.
The report was funded by the National Institute for Health Research.
Emily Beament is the PA environment correspondent.