Learn Icelandic: Ég skelf af því að mér er mjög kalt. - I am shivering because I am very cold.

In Icelandic, feelings of temperature use an impersonal structure. Instead of saying "I am cold" with the subject "I", you express that it is cold to you. Therefore, you use the dative pronoun mér (to me) followed by the "it" form of the verb að vera, which is er.

Why is the adjective kalt (neuter) instead of kaldur or köld, since it describes a person?

Because this is an impersonal sentence, there is no grammatical subject (like ég, þú, or hann) for the adjective to match. The sentence essentially means "to me it is cold." When there is no subject, Icelandic defaults to the neuter singular form of the adjective, which is kalt.

The verb for "to shiver" is að skjálfa. Why does it change so drastically to skelf here?

Skjálfa is a strong verb, meaning it changes its core vowel in the present tense. The já shifts to e in the singular forms, making "I shiver" ég skelf instead of adding a regular ending.

Is af því að always used together to mean "because"?

Yes, af því að is the standard and most common way to say "because" in Icelandic. It literally translates to "from it that." You will usually see these three words grouped together to introduce a reason.