Ef skýin safnast, þá tek ég regnhlífina.

Ef means if.

It introduces a conditional clause:

• Ef skýin safnast = If the clouds gather

So the whole sentence is a conditional statement: if one thing happens, then another thing happens.

Skýin means the clouds.

It comes from the noun ský = cloud.
Here it is:

• plural
• definite

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

So:

• ský = cloud
• ský / skýin depending on form and context, with skýin / skýin meaning the clouds

The ending -in is the attached definite article here.

The accent marks vowel length/quality and is a normal part of Icelandic spelling.

In skýin, the ý is not optional spelling decoration; it is a different vowel from plain y. You should learn Icelandic words with their accents included, because they are part of the word.

Safnast means something like gather, collect, or pile up, depending on context.

The -st ending is very important in Icelandic. It often marks what is called the middle voice. In many cases, this gives a meaning like:

• something happens by itself
• something comes together
• something changes state

So here:

• skýin safnast = the clouds gather / the clouds are gathering together

This is more natural here than using the active verb safna, which usually means to collect something.

Compare:

• Ég safna bókum. = I collect books.
• Skýin safnast. = The clouds gather.

It actually is not singular here.
The form safnast can be the same in singular and plural in the present tense.

So although skýin is plural, the verb form still looks like safnast. That is normal.

In other words, Icelandic does not always show a separate plural ending on the verb in the present tense.

Þá here means something like then.

So the sentence structure is:

• Ef skýin safnast = If the clouds gather
• þá tek ég regnhlífina = then I take the umbrella

It helps mark the result part of the conditional sentence.

In everyday Icelandic, þá is often used in this kind of sentence, but it can sometimes be omitted depending on style and context.

Not always.

You can often hear both patterns:

• Ef skýin safnast, þá tek ég regnhlífina.
• Ef skýin safnast, tek ég regnhlífina.

The version with þá is very clear and natural, especially for learners, because it neatly matches English if ..., then ....

So þá is common and useful, but not absolutely mandatory in every case.

This is because Icelandic is a verb-second language in main clauses.

In the main clause, the finite verb usually comes in the second position. After the opening conditional clause, the sentence continues with þá in first position of the main clause, so the verb comes next:

• þá tek ég regnhlífina

not

• þá ég tek regnhlífina

So the order is:

1. þá
2. tek
3. ég
4. regnhlífina

This word order is very typical in Icelandic.

Tek is the 1st person singular present tense of the verb taka = to take.

So:

• að taka = to take
• ég tek = I take
• þú tekur = you take
• hann/hún/það tekur = he/she/it takes

Since the subject is ég = I, the correct form is tek.

Grammatically it is in the present tense, but it often has a future meaning in context.

That is very normal in Icelandic, especially in conditional and everyday statements.

So:

• Ef skýin safnast, þá tek ég regnhlífina.

can naturally mean:

• If the clouds gather, then I’ll take the umbrella.

Even though Icelandic uses the present form tek, English often translates it with will take.

Regnhlífina means the umbrella.

It is built from:

• regnhlíf = umbrella
• -ina = the definite article in this form

So Icelandic again attaches the to the end of the noun instead of using a separate word.

The word is long because Icelandic packs several pieces of information into one form.

Because the sentence uses the definite form: the umbrella, not just an umbrella or umbrella in general.

So:

• regnhlíf = umbrella
• regnhlífina = the umbrella

If you said tek ég regnhlíf, that would sound more like I take an umbrella / I take umbrella depending on context, and it would not match the definite meaning.

Regnhlífina is in the accusative singular definite.

That happens because taka normally takes a direct object in the accusative.

So:

• ég tek = I take
• what do I take?
  regnhlífina

Also, regnhlíf is a feminine noun, so the ending reflects:

• feminine
• singular
• accusative
• definite

This is one of the big differences from English: Icelandic noun endings often show grammatical case.

The comma separates the if-clause from the main clause:

• Ef skýin safnast, þá tek ég regnhlífina.

This is standard punctuation and helps show the structure clearly:

1. condition
2. result

It works much like English punctuation in If the clouds gather, then I take the umbrella.

Yes, depending on context.

The Icelandic present tense can be fairly flexible.
Skýin safnast can mean:

• the clouds gather
• the clouds are gathering
• sometimes even the clouds start to gather

And tek ég regnhlífina can mean:

• I take the umbrella
• I’ll take the umbrella

The best English translation depends on the situation, but the Icelandic sentence itself is completely natural.

It works, but learners should know there are other ways to talk about clouds and weather too.

For example, Icelandic can also use expressions meaning:

• clouds come together
• it becomes cloudy
• the sky clouds over

So skýin safnast is understandable as the clouds gather, but in real usage you may also meet other weather expressions. That is normal and does not mean this sentence is wrong.

Yes, very much so.

It gives you a useful pattern:

• Ef
  • clause, þá
    • verb + subject + rest

For example:

• Ef það rignir, þá verð ég heima.
  If it rains, then I stay home.

• Ef þú kemur, þá förum við.
  If you come, then we go.

Just remember two key points:

• ef introduces the condition
• the main clause usually follows verb-second word order

That makes this sentence a very good beginner model.