Table 2 The ten-day average air temperature in each month(?)

Month 1 2 3 4 5 6 7 8 9 10 11 12 a year
Month by month 3.4 5.3 10.2 15.5 19.8 23.7 26.3 26 20.3 15.5 9.6 4.9 15
The first ten days of a month 3.3 3.6 8.2 13.6 18.4 22.5 25.4 27.1 22.3 16.7 11.8 6.4 14.9
The middle ten days of a month 3.3 6 10.4 15.7 19.7 23.7 26.1 26.1 20.3 15.8 9.4 4.9 15.1
The last ten-day of a month 3.6 6.5 11.8 17.2 21.1 24.9 27.3 25 18.3 14 7.5 3.6 15