Following sweltering, and in parts record-breaking heat in Sydney on Christmas Eve, a southerly afternoon change led to a dramatic drop in temperatures. Immediately ahead of the change, a line of thunderstorms moving in from the southwest caused a severe thunderstorm warning for damaging winds to be issued for the Illawarra and the Sydney Metro shortly before 1pm. Canterbury had its hottest December day since records began in 1995, reaching 41 degrees before thunderstorms and the change dropped temperatures by seven degrees in just 10 minutes. Bankstown had its second hottest December day with its 43 degrees since records began in 1968, when temperatures soared to reach 43.6 degrees. Sydney also had its second hottest day of the year (tied with Wednesday last week at 38 degrees), since reaching 39.4 degrees late in January. Although no significant rainfall totals from thunderstorms were observed, wind gusts of 40 to 60 km/h were recorded in places like Bankstown, Canterbury, Richmond and the airport. Southeasterly winds are expected to persist along the coast today as light showers persist across the Sydney Basin, but winds should begin to shift more easterly to northeasterly on Boxing Day, just in time for the Sydney to Hobart.