Yes !
It is (very) HOT in summer and nearly impossible to hike from May to September. Even wet-canyoning in Oman is hard in summer.
But this being said : winter-months are fantastic for hiking.
And….many people travel half the world to see the Hajar mountains. Indeed, there are some unique geological features to be admired in this region.
In fact you are looking at the seabed which was lifted hundreds of meters up. It’s not unusual to find marine fossils in these mountains.
Besides fascinating geology, the Hajar mountains offer amazing flora, abandoned villages, beautiful drywalls, terraced fields, fossils, petroglyphs…..It is hiking without trails, completely on your own, with very little backup of rescue teams. Unfortunately without water wells so you need to carry lots of water.
The UAE has only 1 wadi with water year round. It’s Wadi Wurrayah on the east coast. The whole Wurrayah area was declared off limits a few years ago in order to preserve it from increasing and destructive tourism. The WWF is running a major project there for the Sharjah government. Till they re-open the Wadi, your options are to sneak in or to request a guided tour to Sharjah municipality.
The rest of the Hajar mountains is yours to hike. A few years ago Ras Al Khaimahstarted to develop tourism on Jebel Jais. It became an immediate success.
Bikers, cyclists, tourists, car racing, BBQ, Via Ferrata, cool weather: every Friday hundreds of people flock to Jebel Jais. They invade the mountain side in a friendly chaos. Grilling freshly slaughtered goats on make shift barbecues, rolling out carpets alongside the road, having great fun. The flow attracted a few entrepreneur tea stalls and soon you will be able to get a hot dog on the UAE`s highest road.
There are even plans to build the longest and fastest zipline in the world. Any Shihuh with a plot of land along the Jais road sees the value skyrocketing and one can soon expect a few entrepreneurs to open guesthouses along the road.
BUT: none of the Friday Tourists adventures are more than 100 meter from the tar. So all trails are yours and you will seldom meet fellow hikers. Remember: although settlements might look abandoned, they seldom are. They belong to families, Shihuh or Habshi, living in Rak. Please respect the fields and houses.
Since you might get into remote areas without cell phone coverage:
. Tell somebody when and where you are going.
. When you are planning to be back

Take lots and lots of water!!! There is none in the mountains….

Pack light but adequately

Take your GPS and Cell in the mountaoins (albeit poor phone coverage in most areas)