Hi. I am looking for some input on dealing with heat and humidity when playing outside. My bow feels like it has been soaped and I can produce very little sound. any suggestions? I was thinking about investigating the Incredibow as a possible solution. 
The solution might be as simple and inexpensive as switching your rosin.
Be prepared to retune a lot until the instrument stabilizes.
Keep the instrument in it’s closed case out of the direct sun: it can get pretty hot in there.
If you plan on doing this often, it might pay to get a “beater” fiddle for this purpose, and leave your good one at home.