26th August 2025
Base lines shift not only in our psyche but in science too.
“A heatwave is an extended period of hot weather relative to the expected conditions of the area at that time of year, which may be accompanied by high humidity…[It is] met when a location records a period of at least three consecutive days with daily maximum temperatures meeting or exceeding the heatwave temperature threshold.” (1)
Heatwaves are thus relative rather than absolute. As temperatures have risen, so the threshold for a heatwave has increased. (2) In London the threshold was 26C but as of 2022 it is now set at 28C. We have had four heatwaves this summer in London, so I guess it is possible that the threshold marker will be raised again.
(2) https://www.rmets.org/metmatters/shifting-baseline-uk-heatwaves
The Green Tau 