By the time the rain stopped the ambient light was so dim it was hard to capture the texture of the cold lava and also get a good exposure of the red glow.
It was mesmerizing watching the liquid earth flow slowly down the mountainside. A movie would portray this better than a still photo, as it would also record the crackling sound of the lava as it moved.
I did not realize this at the time, but Kīlauea is where most of the conflict between Pele and the rain god Kamapuaʻa took place (Hawaiian mythology). The weather was appropriate.