Sheffield experienced one of the warmest September nights for over a hundred years.
Overnight on September 6, to 7 was the warmest September night since 1898 – and the second warmest ever.
But Sheffield weather experts said the warm September could be linked to a harsher winter with colder temperatures to come.
The weather station at Weston Park, run by Museums Sheffield, recorded an overnight temperature no lower than 17.9C. The temperature in 1898 was 18.2C – just a fraction warmer.
The city also enjoyed the highest daytime temperature in September since 2011 – 27.5C.
September was the joint second warmest on record, equalling 1949, with the average temperature of 16.1C.
The warmest September on record was 2006 at 16.5C – the normal monthly average for September in Sheffield is 13.7.
Alistair McLean, curator of natural science at Weston Park, said the September nights had been consistently warm throughout the month.
He said: “On occasion, you do get warmer days in September and people often talk about if we’re going to get an Indian Summer in September, October time.
“But what’s been interesting this September is the nights have been fairly consistently warm and above average for what you would normally expect and that’s reflected in the high average temperature.
“Another interesting point to make is the last time we had a warm September we had a harsh winter.
“This is something that could be linked – it does seem to be a bit of a trend but without a super computer to crunch the numbers we can’t be sure.
“We know that climate change is a factor, but we don’t know the causes whether it’s part of a cycle or if it’s made by human activity.”
Sheffield is due to be mostly dry for the rest of the week, apart from some light scattered showers on Friday.