If someone told me that they were angry about the bad weather, I would respond empathetically and try to validate their feelings. Here's an example of how I might respond:
"I understand how frustrating bad weather can be. It can disrupt plans and affect our mood. It's completely normal to feel angry or irritated when things don't go as we hope. Is there anything specific about the bad weather that's bothering you, or do you just need to vent? I'm here to listen and support you."