Ser is never used to talk about weather

Question

It is a very important day - Es un día muy importante.

It is a very cold night - Hace una noche muy fría.

I understand it is idiomatic. But why? What is the difference between the two sentences? What if I want to say 'it is a very cold boring day'? Would it be 'es un día muy frío y aburrido'?

P.S. I believe in this example we are talking about a night and its characteristic (cold), not about weather. The test for this lesson needs to be reviewed.

Inma Sánchez · Accepted Answer

Hola Aleksandre,
I checked the test and I removed that specific question. As you say it is a bit ambiguous. Both options would be correct. The one using "hace" would be focusing more on what the weather is like: Hace una noche muy fría ( as in Hace frío) and the sentence using "es" would be more descriptive, it is giving a "characteristic" of the night (Es fría)
So, for your sentence "it is a very cold boring day", you could still use both, "hace un día frío y aburrido" or "Es un día frío y aburrido". However, when we use this idiomatic "hace", we use it with adjectives that talk about the weather: frío, calor... Having the extra word "aburrido" would probably trigger "es", or you would more likely split it: "Hace un día frío y es aburrido"
I hope this clarified it.
Inma

Josefina Davis · Answer

Es un día muy importante - the subject is the type of day ( the description of the day...important) and not necessarily about the weather.
I would say "Hace frío esta noche" for it's a cold night when talking about the weather. I would say Es una noche muy fría because the "fría" is a description for the night and I see the subject as "night" and not the weather. It may be the idiomatic way of expressing yourself in Spain, the expressions for "hace" should be closer connection to talking about and describing the weather. Otherwise, there are many ways of expressing the same thought.

Regardless, this site is excellent for teaching and exploring and learning. These finer points will not ruin your communication with others and can bring up points of discussion if you want to continue to learn. But don't let it keep you form communicating with real people and laughing about the many ways that things can be said. Remember that there is a difference when speaking English in the USA, Britain, Wales, Ireland, Australia, India. etc.