Unfortunately saved golden circle for our last day in Iceland. Received yellow alert notification from our car rental agency, today. We have 4 wheel drive, should I consider canceling trip to gullgoss and thingveller - rainy and windy conditions.
I would not drive with a yellow warning. Stay put. Have you read up on what the warnings mean? We always check the weather and road conditions multiple times each day when we are there.
Do not take weather warnings lightly in Iceland. Apart from the driving being harder, you might also want to ask yourself if you will enjoy visiting the sites if it's very windy and heavy rain.
You don't mention what car you have, but a smaller car would be better if you still plan on doing the trip.
I checked vedur.is and, there’s no bleeping way I’d drive to gullgoss or thingvellir. And I drive in crappy winter weather all the time
What would be the point anyway once you got there?