You already have four of the temperatures, since you know the median is -1.3C (one of the days must be this temperature) and the mode is -2.4C (two days must be this temperature. We can't have any more than two days be this temperature since the median was -1.3C, only two values can be less.) You are also told the maximum temperature is 4.5C. This leaves you to find the last temperature, call it x. Since the mean is 0C, that means

[(-2.4) + (-2.4) + (-1.3) + x + 4.5]/5 = 0

Solve for x.