Quick Look

Monthly temperature data were obtained from NCDC climate station data. More information on the dataset can be found here.

Climatology
The climatologies of temperature in both Salalah and Masirah climate station show a similar double peak (compare figures 1b and 2b). However, the reason for this same feature may be different.
Masirah lies on an island which is located in the middle of the upwelling region (compare SST). Due to the upwelling the temperature of the Arabian Sea near Masirah lower in summer than in spring and fall. The monsoon winds therefore bring cooler air to the island.
However, for Salalah an alternative explanation for low summer air temperature can be found. Salalah is cloud covered from June to August. The incident solar radiation is thus low and this is the reason why the temperature drops. When the clouds disappear the temperature increases again until the sun moves far away to the southern hemisphere in winter.

Salalah [17.02 N , 54.05 E] elevation 20 m

Masirah [20.40, 58.54] elevation19 m

Thumrait [17.40 N , 54.02 E] elevation 467m