The spring is unusually early this year and the lupine is beginning to wake up and when the picture was taken late in the afternoon, the temperature was around 15°C which is not usual at this time of year but it has happen before though.
The water surface of Rauðavatn is unusually high now, but as I have said before, no surface runoff is from the lake. It is because the lake lies in a fissure swarm connected to a central volcano so that the water seeps through the bedrock.