When travelling, it's generally smart to pack in preparation for rain or any other conditions that may arise. The rainfall in Narita is roughly greater than that of Al Ain. You can assume this to be the case over the next 16 days.
You can imagine temperatures to be in the 45 °C range in July. The weather in Al Ain is generally hotter than Narita's. As flight availability is subject to become more limited as peak season approaches it is ideal to book in a timely manner.