I struggle with translating "the weather is very good." My inclination is to write "el tiempo está muy bueno," because it is acceptable to use está for some weather related expressions per your very helpful guidelines.

Is there any 100% reliable way that you can suggest for when to use hace vs está. Is it a matter of learning off these phrases / expressions and that they are invariable? Is anything to do with "temperature, cold, hot and weather" always expressed using hace?

Finally if I wanted to say "In Rome, there is good weather today." Could I say "En Roma hay buen tiempo hoy?" or  is this invariably expressed using hace?" Thanks John