Ef veðrið versnar, gætu þau þurft að aflýsa símafundinum í kvöld.

Because Icelandic is a V2 language in main clauses: the finite verb normally comes in the second position.

Here, the whole subordinate clause Ef veðrið versnar takes the first slot. That means the next element must be the finite verb of the main clause, gætu, and only after that comes the subject þau.

So:

• Ef veðrið versnar, gætu þau þurft...
• but on its own: Þau gætu þurft...

This word order is one of the most important differences from English.

Gætu is the 3rd person plural subjunctive past form of geta.

In this sentence, it expresses a possibility or uncertain outcome, similar to English might or could. That is why it fits well in a sentence like this: the cancellation is only a possible consequence if the weather gets worse.

It agrees with þau, which is plural.

A helpful way to think of it is:

• geta = can / be able to
• gæti / gætu = might / could

Þau is the neuter plural form of they.

Icelandic uses þau in several situations, especially:

• for a mixed-gender group
• for a group whose gender is unknown or not important
• for some non-human plural nouns
• sometimes in a more neutral, general sense

So in a sentence like this, þau is a natural way to say they without specifying gender.

Because veðrið is the definite form: the weather.

Icelandic usually puts the definite article on the end of the noun, instead of using a separate word like English the.

So:

• veður = weather
• veðrið = the weather

It is also the subject of versnar, so here it is in the nominative singular.

English often uses bare nouns where Icelandic prefers a definite form, especially when talking about the specific weather conditions being discussed.

Versnar is the 3rd person singular present tense of versna, meaning to get worse / worsen.

Even though the whole sentence refers to a future possibility, Icelandic often uses the present tense in an if-clause like this, just as English normally says:

• If the weather gets worse...

not usually:

• If the weather will get worse...

So the present tense here is completely normal.

This is a very common Icelandic pattern:

• gæti/gætu þurft að + infinitive

It means might need to + verb.

The form þurft is the non-finite form used here; grammatically, it is the supine form of þurfa (it has the same shape as the neuter past participle). For a learner, the easiest approach is to remember gæti/gætu þurft að as a set expression meaning might need to.

So:

• gætu þurft að aflýsa = might need to cancel

Because þurfa normally takes að + infinitive.

So you get patterns like:

• þurfa að fara = need to go
• þurfa að bíða = need to wait
• þurfa að aflýsa = need to cancel

In this sentence, the að belongs with aflýsa after þurft.

The dictionary form is símafundur, meaning phone meeting or conference call.

It is a compound:

• síma- = phone, telephone
• fundur = meeting

In the sentence, it appears as símafundinum, which is:

• singular
• definite = the phone meeting
• dative

So the rough breakdown is:

• símafundur = phone meeting
• símafundurinn = the phone meeting (nominative)
• símafundinum = the phone meeting (dative)

Because the verb aflýsa takes the dative.

This is something you have to learn with the verb:

• að aflýsa einhverju = to cancel something

So:

• aflýsa fundinum = cancel the meeting
• aflýsa ferðinni = cancel the trip
• aflýsa símafundinum = cancel the phone meeting

This is a good example of why it is useful to learn Icelandic verbs together with the case they govern.

Í kvöld is a common time expression meaning tonight / this evening.

It is functioning as an adverbial phrase of time. Putting it at the end of the sentence is very natural in Icelandic.

You can think of it as answering when?

• gætu þau þurft að aflýsa símafundinum í kvöld
• They might have to cancel the phone meeting tonight

This phrase is often treated as a fixed expression. It uses í with the form kvöld in an adverbial time expression. You may also see similar phrases like:

• í dag = today
• í morgun = this morning
• í nótt = tonight / during the night

In this sentence, í kvöld will usually be understood as referring to the time of the meeting or the relevant event in the evening.