The sandstorm is one thing Funcom got right… it never causes lag, it looks great, but what happened to the sandstorm beasts that were supposed to accompany it? Sandstorm beasts hit like trucks, however there could be a rare version of the storm with a dark red sky, a little extra warning, maybe 5 minutes, where sandstorm beasts fade into existence. Give us something to fear while leveling up or farming, adds to the risk of being caught out.
Other zones should definitely have storms as well, blizzards in the north, drifting into the tundra area, causing freezing rain in the mounds of the dead, flurries in the highlands, a hurricane in the rainforest, a firestorm in the volcano where you literally can only survive with extremely high heat resistance (mismourn shield, legendary gear from unnamed city, maybe even eating ice). Or a creepy gaseous green mist in the mounds of the dead every so often with things lurking within.
Even further thoughts, rare pets could accompany these storms, tameable in some difficult way or another.
It would be an exciting feature of the game in my opinion, all that heat resistent/cold resistent/gas protection equipment could have a good use. Proper gear such as masks could help clear up vision as well.