Visit Dubai gives these average temperatures: 21°C in January, 22°C in February, 24°C in March, 28°C in April and 31°C in May; 34°C in June, 36°C in July, 35°C in August and 34°C in September; then 31°C in October, 27°C in November and 24°C in December.
Daytime highs run hotter than those averages. The World Meteorological Organization's figures for Dubai, supplied by the UAE's National Center of Meteorology, put average highs above 40°C in July and August, while January's average low is 13.7°C.
Rain is rare in any month. On the same figures, February and March, the wettest months, average fewer than 4 days of rain each, and June to October almost none.