Sources have included published papers, university and council archives and history books.
"The records show that the warm weather in October that we have witnessed this year is not unique," said Mr Rothwell.
"All sorts of unusual weather has occurred during all the seasons in central England in the past."
The Central England Weather Series includes information about a famine in 1258, which killed 20,000 people, and a thunderstorm in the summer of 1588, which destroyed two Nottinghamshire towns.
Mr Rothwell said his personal interest in meteorology stemmed back to World War II.
"During the war weather reports were secret," he said.
"As a young boy I remember going to bed and being surprised to wake up to six inches of snow. I wanted to know why," he said.
His records have been donated to the Nottinghamshire County Council archives service and will eventually be given to to the national Met Office archives.
Until then, Mr Rothwell said he would continue to add to the collection.
1258: A very wet and cool summer led to the failure of crops and an appalling famine which was one of the worst in English history. Twenty thousand people starved to death in London alone.
1458: Floodwater and ice floes destroyed the bridge over the River Trent after a very cold and snowy winter.
1588: A severe thunderstorm accompanied by a tornado and large hail destroyed the towns of Lenton and Wilford, killing five people on 17 July.
1635: A severe winter blizzard led to snowfall with drifts up to 20 feet deep.