https://www.thejournal.ie/research-kilkenny-castle-1887-hottest-temperature-record-5820271-Jul2022/
The below is interesting as the assumption from some on here was that the 33.3 was totally representative of conditions in Ireland and the UK at the time.
"The reanalysis also compared the temperature recorded in Kilkenny to six other weather stations, including in Birr, Phoenix Park, Roches Point, and Sheffield in the UK.
These stations have nearly complete records through to today, many of which have been digitised, according to the study.
The maximum surface temperatures of the selected weather stations for June 1887. The red point marker shows the maximum surface temperature recorded at Kilkenny on 26 June 1887.
“We can look at the modern day differences between those and when we look at the date in 1887, the Kilkenny Castle difference is either entirely outside the distribution of expected daily occurrences or right in the extreme of that distribution,” Thorne said.