After six days in early July with temperatures over 40 °C (104 °F), Portugal officially entered a heat wave. Temperatures reached as high as 45 °C in some places in Alentejo and Ribatejo. Rising temperatures led to heat health warnings being issued for Southern England and the Midlands in the UK's first prolonged heatwave since 2006 on 17 July. The UK recorded its hottest day since July 2006, with 33.5 °C (92.3F) recorded at Heathrow and Northolt in west London on 22 July. This was later beaten again on 1 August, when 34.1 °C was recorded at Heathrow Airport. Epidemiological statisticians at the London School of Hygiene &amp; Tropical Medicine using models developed in 2011 estimated the heatwave in England and Wales would have led to the premature deaths of 650 people. London Fire Brigade reported that it had attended on average 29 grass fires a day between 1–21 July, seven times the number of call outs for grass fires than the same period in 2012. In Hungary the July heatwave set new daily records for the 27th, 28th and 29th being the hottest day of the year with 40 °C only 2 degrees from the absolute record. A day earlier the 2013 Hungarian Grand Prix was the 2nd hottest in recent Grand Prix history just behind the 2005 Bahrain Grand Prix. Track temperature reached 56 °C and air temperature was 38 °C.