One thing that I have found is that sometimes the weather changes at a moments notice. This is a subject that could make you think twice about not having a studio. I know I am writing this when the weather is very hot and humid. The thing is though I am not great in hot weather, as where during wet weather I am normally not shooting for the camera kit.
I will go out in the hot humid stuff so that I can get some amazing shots but you still have to check for where the sun is so you can shot in the shad. I say this as the sun can be very bright and there will be extreme shadow and light on the model. These can be hard to balance out. That is the main help of things like reflectors and anything that will soften the light that you are working with.
You can also shoot with the sun behind the model, which will give you a chance to have a halo around the model. You can use your reflector to bounce the light onto the models face. I can sometimes be bright on the model so normal I use the edge of the reflector as this will be a softer light on the model than in the middle, as it is very bright like shooting a mirror in there faces. Doing this would make a very bad photo as the model would be pulling faces.
The other way is using a flashgun as this is an easier thing to sort on your own then a reflector as there could be a windy day, and it will be blowing about. This is something that does not happen with a flash gun.
When it rains or due to rain I would try and find a place near or in a tunnel. I would Just use this a studio as I can make the light bounce all over the place and is the great fun thing to do.
I would also keep water on me in the hot weather as I would get through alot of it on the hotter days. Just when it is cold I do wrap up and try and stay warm. These are things that go through my head when planning my shoots as sometimes I cancelled due to the weather.
I do hope this helps you with your shots.