September kan være kald.

Because it is the first word in the sentence.

In Norwegian, names of months are normally written with a lowercase letter: september, oktober, november, and so on. But at the beginning of a sentence, they take a capital letter just like in English.

So:

• September kan være kald. = capitalized because it starts the sentence
• I september kan det være kaldt. = lowercase because it is in the middle of the sentence

Kan være is a combination of:

• kan = present tense of kunne
• være = infinitive to be

Together, kan være means can be or may be.

In this sentence, it expresses possibility or a general truth, not ability. So it means something like:

• September can be cold
• September may be cold
• September is sometimes cold

Because kald is the form used here with September as the subject.

The adjective kald changes form depending on how it is used:

• kald = common gender / singular base form
• kaldt = neuter singular
• kalde = plural / definite

Here, September is being treated as a singular noun, and the normal form in this kind of sentence is kald:

• September kan være kald.

But if you use det as the subject, you usually get kaldt:

• Det kan være kaldt i september. = It can be cold in September.

So both are correct, but they are built differently.

Because September is the name of a month, and month names normally do not take an article.

Just as in English, you usually say:

• September er fin.
• Jeg liker september.
• Vi reiser i september.

Not:

• en september in this meaning

So September works like a proper name here.

It is correct, but many learners will also hear a very common alternative:

• Det kan være kaldt i september.

This version is often more natural in everyday speech because Norwegian frequently uses det in weather-style expressions.

So you may see both:

• September kan være kald.
• Det kan være kaldt i september.

The first focuses on September as the topic. The second sounds a bit more like a typical weather statement.

The sentence follows normal Norwegian main-clause word order:

• September = subject
• kan = finite verb
• være = infinitive
• kald = adjective complement

So the pattern is:

subject + verb + infinitive + adjective

This is similar to English:

• September can be cold.

No, not really.

In this sentence, kan does not mean that September has the ability to do something. It expresses possibility or what is sometimes the case.

So:

• Hun kan svømme. = She can swim. → ability
• September kan være kald. = September can be cold. → possibility

This is a very common use of kan in Norwegian.

Yes, but the meaning changes slightly.

• September kan være kald. = September can be cold / is sometimes cold
• September er kald. = September is cold

The version with kan is softer and more general. It suggests that cold weather in September is possible or typical, but not always true.

The version without kan sounds more definite.

A simple learner-friendly pronunciation guide would be:

• September ≈ sep-TEM-ber
• kan ≈ kahn
• være ≈ VAIR-uh or VEH-reh depending on accent
• kald ≈ kahld

A few useful notes:

• The r in Norwegian is usually pronounced more clearly than in many English accents.
• æ in være is a front vowel that does not sound exactly like English a.
• The d in kald may be weak or not strongly released in natural speech.

Pronunciation varies by dialect, so you may hear different versions.

In this sentence, no. It is understood as talking about temperature.

Because the subject is September, the adjective kald is naturally interpreted as cold in weather/temperature.

So:

• September kan være kald. = the weather or temperature in September can be cold

The emotional meaning of cold does exist in other contexts, but not here.