Winters in Hanwell are generally cool and wet, with temperatures ranging from around freezing point to mid-teens. Spring is a period of gradual warming, with temperatures slowly rising into the double digits by March. By May, temperatures can reach up to 23°C, marking a significant increase in warmth. Summers are warm but not hot, with July being the warmest month on average at around 18°C. In autumn, temperatures drop back down, returning to cooler averages by October and November.