Ég fer í peysu þegar mér er kalt.

Fer is the 1st person singular present tense of the verb fara, which usually means to go.

So:

• ég fer = I go
• að fara = to go

In this sentence, though, fara is part of the expression fara í, which has a special meaning with clothing.

With clothes, fara í often means to put on or to get into a piece of clothing.

So:

• fara í peysu = put on a sweater
• literally, it is closer to go into a sweater, but English does not say it that way

This is a very common Icelandic way to talk about putting on clothes:

• fara í jakka = put on a jacket
• fara í skó = put on shoes

Most directly, ég fer í peysu suggests the action I put on a sweater.

But in natural English, the whole sentence can also be translated as I wear a sweater when I’m cold, because it describes a usual habit.

So the Icelandic form focuses a bit more on getting dressed in it, while English may choose either:

• I put on a sweater when I’m cold
• I wear a sweater when I’m cold

Both can fit the general meaning.

Because the preposition í can take different cases, and with fara í it normally uses the accusative to show movement into something or into a new state.

The noun peysa is a feminine noun:

• nominative: peysa
• accusative: peysu

So:

• í peysu = into a sweater / putting on a sweater

A small detail: for this word, the accusative and dative singular happen to look the same: peysu. But the case used here is accusative because of fara í.

Icelandic does not have a separate indefinite article like English a/an.

So peysu can mean:

• a sweater
• sometimes just sweater in a general sense

If you want the sweater, Icelandic usually adds the definite article to the end of the noun:

• peysan = the sweater (nominative)
• peysuna = the sweater (accusative)

So:

• í peysu = in/into a sweater
• í peysuna = into the sweater / putting on the sweater

This is one of the most important Icelandic patterns to learn.

For physical feelings such as cold, hot, hungry, and similar states, Icelandic often uses an impersonal construction:

• mér er kalt = literally to me is cold
• natural English: I am cold

So Icelandic does not usually say ég er kaldur/köld for I am cold in the sense of feeling cold.

If you said ég er kaldur or ég er köld, it would sound more like I am cold/cold-hearted/cool to the touch, describing a quality rather than the temporary bodily sensation.

Mér is the dative form of ég.

The pronoun forms are:

• nominative: ég = I
• accusative: mig = me
• dative: mér = to me / for me

In the expression mér er kalt, Icelandic uses the dative experiencer:

• mér er kalt = I am cold
• literally: to me is cold

This pattern is very common:

• mér er heitt = I am hot
• mér er illt = I am in pain / it hurts
• mér er sama = I don’t care / it’s all the same to me

In this kind of impersonal expression, the adjective is usually in the neuter singular form.

That is why you get:

• kalt = cold
• heitt = hot
• illt = painful / bad

It does not agree with the speaker’s gender here. So both a man and a woman can say:

• mér er kalt

That is different from sentences where an adjective agrees with the subject, such as:

• ég er kaldur = I am cold/cool (male speaker)
• ég er köld = I am cold/cool (female speaker)

But again, for the feeling of being cold, mér er kalt is the normal pattern.

Here þegar means when.

So:

• þegar mér er kalt = when I am cold

Because the whole sentence is in a general, habitual present, þegar can also feel like whenever in English:

• I put on a sweater whenever I’m cold

Do not confuse it with ef, which means if.

• þegar mér er kalt = when I’m cold
• ef mér er kalt = if I’m cold

Because mér belongs directly to the impersonal expression mér er kalt.

So the clause is built as:

• þegar = when
• mér = to me
• er = is
• kalt = cold

In other words, mér er kalt stays together as the normal Icelandic pattern for I am cold.

This can feel unusual to English speakers, but it is a standard Icelandic structure. You should learn mér er kalt as a whole phrase.

Yes.

Nothing in Ég fer í peysu þegar mér er kalt tells you whether the speaker is male or female.

That is because:

• ég does not show gender
• mér does not show gender
• kalt is neuter because of the impersonal construction, not because of the speaker’s gender

So the sentence works the same for anyone.