I marts føles foråret ofte tæt på, selvom det stadig kan være koldt.

Danish uses i with months to mean in a particular month:

• i marts = in March
• i april = in April

So i marts is the normal expression here.

This is because Danish main clauses follow the V2 rule: the finite verb must come in the second position.

Here, I marts takes the first position, so the verb føles has to come second:

• I marts | føles | foråret ...

If the subject came first, you could say:

• Foråret føles ofte tæt på i marts.

Both are grammatical, but the original sentence puts focus on March.

Føler is the ordinary active form of føle = to feel.
But føles is the -s form, which here gives a meaning like feels or is experienced as.

So:

• foråret føles tæt på = spring feels close

This does not mean that spring is doing the feeling. It means that spring is experienced as being near. English often uses the same kind of idea: It feels strange, The room feels warm, Spring feels close.

It looks like a passive form, and historically it is related to the Danish -s passive, but in sentences like this it is often best understood as a middle/passive-like form meaning seems/feels.

So foråret føles tæt på is not really about an action being done to spring. It is about how spring is perceived.

Foråret is the definite form: the spring.

Danish often uses the definite form when talking about seasons as familiar, recurring parts of the year:

• foråret = spring / the spring
• sommeren = summer / the summer

English usually says just spring, but Danish often prefers foråret in this kind of sentence.

Tæt på is a very common expression meaning close or near.

It can be physical:

• Han står tæt på døren = He is standing close to the door

Or figurative, as in this sentence:

• foråret føles tæt på = spring feels close / near

So here it suggests that spring seems as if it is almost here.

Ofte means often. In Danish main clauses, adverbs like ofte commonly come after the finite verb, or after the subject if the subject has moved behind the verb because of V2 word order.

Compare:

• Foråret føles ofte tæt på.
• I marts føles foråret ofte tæt på.

In the second sentence, I marts comes first, so the verb moves into second position, and ofte stays later in the clause.

Selvom means although / even though. It introduces a subordinate clause:

• selvom det stadig kan være koldt

That clause adds a contrast: spring may feel close, although the weather can still be cold.

You may also see selv om in some texts, but selvom is very common and standard here.

Because subordinate clauses in Danish usually have a different word order from main clauses.

In a main clause, you would normally say:

• Det kan stadig være koldt.

But after a subordinating conjunction like selvom, adverbs such as stadig usually come before the finite verb:

• selvom det stadig kan være koldt

So this is a normal subordinate-clause pattern.

Here det is a dummy subject, just like English it in sentences such as:

• It is cold
• It can still be cold

It does not refer to a specific noun. It is just the grammatical subject needed for the weather/condition statement.

Because the adjective is used with det, which takes the neuter singular form of the adjective in this kind of sentence.

So:

• det er koldt = it is cold
• vejret er koldt = the weather is cold

But with a common-gender noun, you would get:

• en dag er kold = a day is cold

So koldt is the correct form here.

Kan være adds the idea of possibility:

• det kan være koldt = it can be cold / it may be cold

That fits the meaning well: even though spring feels near, cold weather is still possible.

If you said det er stadig koldt, that would sound more definite: it is still cold. The original sentence is a bit softer and more general.

It is very common to put a comma before a subordinate clause like this, especially in more traditional comma use:

• ..., selvom det stadig kan være koldt.

In some modern writing, the comma may be omitted. So the comma here is very normal, but you may also see the sentence written without it.