- An analysis by the National Trust found that 24 degrees Celsius (75.2 degrees Fahrenheit) was the optimum temperature for visits to its outdoor sites.
- However, the charity found visitor numbers started to decline above that point and "dramatically reduce" when it reached 28 degrees Celsius.
Britain's nature and historical preservation organization, the National Trust, is considering giving staff Mediterranean working hours in the event of "extreme temperatures" due to climate change.
The National Trust said on Wednesday that it had already introduced a change to working hours at its historical Ham House site in Surrey, England, to ensure that employees working outdoors could avoid the midday sun on days of "extreme heat."
However, a spokesperson for the charity told CNBC it had not yet adopted the policy.
"There are other locations that 'may' consider this as an option as the climate warms and only in exceptional circumstances but the data is largely focused around visitor patterns," the spokesperson said.
Get Tri-state area news and weather forecasts to your inbox. Sign up for NBC New York newsletters.
In the case of Ham House, they explained that employees were able to start earlier and take a break at the hottest time of the day.
The National Trust said it had analyzed data from more than 85 million visits to 170 of its U.K. sites between 2015 and 2019, plotting this against weather patterns. It found that 24 degrees Celsius (75.2 degrees Fahrenheit) was the optimum temperature for visits to its outdoor sites but visitor numbers started to decline above that point and "dramatically reduce" when it reached 28 degrees Celsius.
With hotter summer days expected in the coming years, the National Trust said this could have "huge implications for the tourism sector" and could see the peak season shift from July and August to the fall months.
National Trust head of climate and environment Lizzy Carlyle said that much of the "debate around tourism and climate change to date has rightly focused on international travel and the impact flights and foreign holidays is having."
However, she added that the effects on domestic tourism had not been fully addressed and the challenge to "adapt to changes in the U.K. climate should not be underestimated."
In addition to adopting flexible working hours for staff, the National Trust is also creating shade to cover outdoor seating using "flora that is resistant to higher temperatures."
In areas more prone to flooding such as the Lyme Park estate in Cheshire, in northwest England, the National Trust is planting more trees and shrubs to protect car parks and the property.
The charity is also planting trees away from buildings and areas with more visitors, where they are more prone to falling should the severity of storms and high winds increase.
However, if emissions aren't reduced, the National Trust said it may mean that an "increasing number of stately homes and indoor tourist attractions are forced to temporarily close more often due to excessive heat and storms."