The Mallee and upper Wimmera are Victoria's warmest regions with hot winds blowing from nearby semi-deserts. Average temperatures exceed 32 °C (90 °F) during summer and 15 °C (59 °F) in winter. Except at cool mountain elevations, the inland monthly temperatures are 2–7 °C (4–13 °F) warmer than around Melbourne (see chart). Victoria's highest maximum temperature since World War II, of 48.8 °C (119.8 °F) was recorded in Hopetoun on 7 February 2009, during the 2009 southeastern Australia heat wave.
Where can we find proof for inland temperatures?