LONDON, ENGLAND - SEPTEMBER 14: Horse riders from Hyde Park Barracks trot through Hyde Park at sunrise on September 13, 2016 in London, England. Areas in the South East of England continue to enjoy seasonable weather. (Photo by Dan Kitwood/Getty Images)

TOPSHOT - Windows are opened in a high rise building as mild spring weather arrives in Sydney on September 14, 2016. / AFP PHOTO / PETER PARKSPETER PARKS/AFP/Getty Images

LONDON, ENGLAND - SEPTEMBER 14: Horse riders from Hyde Park Barracks trot through Hyde Park at sunrise on September 13, 2016 in London, England. Areas in the South East of England continue to enjoy seasonable weather. (Photo by Dan Kitwood/Getty Images)

LONDON, ENGLAND - SEPTEMBER 14: Horse riders from Hyde Park Barracks trot through Hyde Park at sunrise on September 13, 2016 in London, England. Areas in the South East of England continue to enjoy seasonable weather. (Photo by Dan Kitwood/Getty Images)

LONDON, ENGLAND - SEPTEMBER 14: A horse rider from Hyde Park Barracks trots through Hyde Park at sunrise on September 13, 2016 in London, England. Areas in the South East of England continue to enjoy seasonable weather. (Photo by Dan Kitwood/Getty Images)

LONDON, ENGLAND - SEPTEMBER 14: Horse riders from Hyde Park Barracks trot through Hyde Park at sunrise on September 13, 2016 in London, England. Areas in the South East of England continue to enjoy seasonable weather. (Photo by Dan Kitwood/Getty Images)

LONDON, ENGLAND - SEPTEMBER 14: Horse riders from Hyde Park Barracks trot through Hyde Park at sunrise on September 13, 2016 in London, England. Areas in the South East of England continue to enjoy seasonable weather. (Photo by Dan Kitwood/Getty Images)

Office workers enjoy the sunshine as mild spring weather arrives in Sydney on September 14, 2016. / AFP PHOTO / PETER PARKSPETER PARKS/AFP/Getty Images