Yes, it is a safety issue, wiring should always be covered by something, anywhere. The connection should be water tight, the connector used is not. Electric proof is not an issue, that is the job of the insulation of the wires. Cold resistant is not an issue for the wiring, but could be an issue if the cold made some protective material brittle. Protection from weather is an issue, you do not want water or debris entering the wiring space.
I suspect the back fill that the tubing is placed in settled, pulling the buried portion away from the above ground portion. If you can't pull the sections together to reattach, you may have a problem. It may be worth digging up the tubing to get more play to reattach, as the only code compliant fix I know of is to either replace the entire run, reusing materials where possible, or insert a new box to make up for the gap. You'll have to cut the wires to place the box. There may be enough slack to reattach them, otherwise, pigtail them together with short new lengths. Be sure to use water tight box and connectors if you go this route. The box must remain accessible.
I shouldn't even mention this. The hillbilly fix would be to get a length of plastic water tubing, the thin walled gray stuff (PB?) is what I've seen, of adequate diameter. Slit it along it's length, wrap it around the open joint, and seal the overlap and the tubing above and below with silicone sealant. Clamp in place with several screw type hose clamps. Far from code compliant but it adequately protects the wiring. More water tight than the current connector.