In January the average maximum daytime temperature in Dubai is 24 °C (75 °F). The average rainfall is 10 mm (0.4 inches) of, with rain generally falling on just two days of the month.While the average sea temperature in January is 22 °C (72 °F).n January the average maximum daytime temperature in Dubai is 24 °C (75 °F). The average rainfall is 10 mm (0.4 inches) of, with rain generally falling on just two days of the month.