When the window is open Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Bar height is a rough guide to midday heat, not an exact reading.
October through April is the stretch most riders in the UAE actually use.
Riders pulled over at a mountain overlook along a UAE riding road
A rest stop along one of the UAE's mountain routes, popular once the weather turns.

Plan routes and track your climbs on both roads in Live Maps, built around exactly these kinds of rides.

Sources