Fluctuations in daily observed and predicted mortality rates, in France in the summer of 2003. (a) Fluctuation in daily minimum (broken blue) and maximum (red) temperatures, and observed mortality rates (black) in France from 1st June to 30th September, 2003. (b) Fluctuations in daily observed (black) and predicted mortality rates, by model with 1 groupa (blue) and 4 groupsb (red), and by model with cubic spline functions for minimum and maximum temperatures c (green), in France from 1st June to 30th September, 2003. X-axis: days from 1st June to 30th September (122 days). Y-axis: daily mortality rate (deaths/100,000/day). a 1 group: G2; b 4 groups: G2, GMA, GCum1t, Gcum1t-2; c model with natural cubic spline functions (6 df) for minimum and maximum temperatures of same-day and 2 lag days.