A la primavera, l'aire és més calent que al novembre.

In this expression, a is part of a time phrase. Catalan often uses a + article for times and seasons where English uses in.

• a la primavera = in spring
• a l'estiu = in summer
• a la tardor = in autumn
• a l'hivern = in winter

So here a la does not mean a literal to the. It is just the normal Catalan way to express this time setting.

Catalan often uses the definite article with seasons and many other nouns in cases where English does not.

So Catalan says:

• la primavera
• l'estiu
• la tardor
• l'hivern

Even when English would simply say spring or in spring, Catalan commonly keeps the article.

Aire is a masculine singular noun, and the definite article is el.
But before a vowel sound, el usually becomes l'.

So:

• el aire → l'aire

This is called elision. It is very common in Catalan:

• l'aigua
• l'home
• l'amic

So l'aire means the air.

És with an accent is the 3rd person singular of ser: is.

• l'aire és calent = the air is warm

The accent helps distinguish it from es, which is an unstressed pronoun in Catalan.

So:

• és = is
• es = reflexive/object pronoun in other contexts

The accent is important and should be written.

Més means more.

In this sentence:

• més calent = warmer / more warm

The accent distinguishes it from mes, which can mean month in Catalan.

So:

• més = more
• mes = month

This accent is very important because the two words mean different things.

Catalan usually forms the comparative with més + adjective.

So:

• més calent = warmer
• literally: more warm

Other examples:

• més gran = bigger
• més interessant = more interesting
• més fred = colder

Unlike English, Catalan does not usually add a special ending like -er to adjectives.

Because calent agrees with l'aire, and aire is masculine singular.

So the adjective must also be masculine singular:

• l'aire és calent
• la sopa és calenta

Agreement matters in Catalan. Adjectives usually match the noun in gender and number.

After que in a comparison, Catalan often uses the same kind of prepositional time phrase again.

The full idea is:

• A la primavera, l'aire és més calent que al novembre.
• literally: In spring, the air is warmer than in November.

Here al novembre = a + el novembre.

So:

• al novembre = in November / in the month of November

Catalan keeps the preposition and article here, where English just says than in November.

Al is a contraction of a + el.

• a + el novembre → al novembre

This is very common in Catalan:

• al matí = in the morning
• al carrer = in the street / to the street, depending on context
• al novembre = in November

So the l comes from the masculine singular article el.

The phrase A la primavera is an introductory time expression: it sets the scene before the main statement.

So the sentence is structured like this:

• A la primavera, = In spring,
• l'aire és més calent que al novembre. = the air is warmer than in November.

The comma helps separate the introductory phrase from the main clause. In short sentences, punctuation can vary a little, but this comma is perfectly natural.

Yes, you may see it without the comma, especially in less formal writing. The meaning does not change.

• A la primavera, l'aire és més calent que al novembre.
• A la primavera l'aire és més calent que al novembre.

Both are understandable. The version with the comma makes the introductory time phrase clearer.

It often can be, especially in expressions like al novembre.

Catalan commonly uses articles with months in certain contexts:

• al novembre
• el novembre passat = last November
• el novembre de 2023

But usage can vary depending on the exact structure and regional preference. In this sentence, al novembre is completely natural.

Here que means than in a comparison.

• més calent que al novembre = warmer than in November

In Catalan, que is the normal word used after comparatives:

• més gran que = bigger than
• més ràpid que = faster than
• més car que = more expensive than

So in this sentence, que introduces the second part of the comparison.

The core sentence is:

• l'aire és més calent que al novembre

This breaks down as:

• l'aire = subject
• és = verb
• més calent = adjective phrase
• que al novembre = comparison phrase

Then A la primavera is added at the beginning as a time phrase.

So the overall structure is:

time expression + subject + verb + comparative adjective + comparison

Yes. Grammatically, més calent literally means more warm, but in natural English we usually translate it as warmer.

So:

• literal meaning: more warm
• natural English meaning: warmer

This is very common when translating Catalan comparatives into English.