With no wx radar or a old one and unpressurized, just fly as far as practicable away from the lightening on the upwind side and stay as low as possible for warmest temperature, ideally well below the freezing level, so you wont get hit by the biggest chunks of ice.
I flew twin otter and embraer 110 through some nasty weather at day and night, summer and winter, and im still alive
during winter its is more dangerous as u can go through severe icing and be covered with ice in a matter of just a few seconds, your only option is at the first sign of icing do a 180 back, I once experience severe icing on a 12 DME arc at night SA and FT were all ok no icing or wx forecast at the airport, but I went through a cloud at night before intercepting the localizer, it last for only a few seconds and I was covered in ice so bad that I decided to continue as a 180 would have brought me down without a doubt, I exited the cloud after a few secs and was going down the ils with max continuous power yes MCT, and I touched down at MCT, that happened once in my 27 years of flying. There was nothing else to be done in that situation, I was just lucky enough for the cloud to be just big enough to keep me flying. At night with no wx radar during winter and no lightening from the cloud is the most dangerous situation. That happened in the north of Canada. of course you will say what? no wx radar, consider this I had a wx radar but lets say it was not picking up anything as the old technology was not as good as today. If u want to stay alive, just don't continue the flight path if you have any doubt or questions in your head, as you pick up experience you will learn how to evaluate the power of mother nature in any given situation more accurately. Stay safe