Öppettiderna ändras på sommaren, så kontrollera hemsidan först.

Öppettiderna means the opening hours, while öppettider means opening hours in a more general sense.

The -na ending is the definite plural ending.
So:

• öppettider = opening hours
• öppettiderna = the opening hours

In this sentence, it refers to the specific opening hours of a particular place, so Swedish uses the definite form.

Ändras means are changed or change here.

The -s form in Swedish is often used as a kind of passive or middle/passive-like form. In this sentence, öppettiderna ändras means:

• the opening hours change
• or more literally, the opening hours are changed

The focus is on the fact that they change, not on who changes them.

Compare:

• De ändrar öppettiderna. = They change the opening hours.
• Öppettiderna ändras. = The opening hours are changed / change.

Yes, but it would sound a bit different.

• ändras = change / be changed
• förändras = change, often with a stronger sense of become different

In everyday practical information like this, ändras is the most natural choice. It is simple and common for schedules, prices, times, rules, and similar things.

In Swedish, på sommaren is the normal way to say in summer or during the summer when talking about a recurring time period or season in general.

So:

• på sommaren = in summer / during the summer
• på vintern = in winter
• på hösten = in autumn
• på våren = in spring

English uses in, but Swedish usually uses på with seasons in this kind of sentence.

Sommaren is the definite form of sommar:

• sommar = summer
• sommaren = the summer

But in Swedish, expressions like på sommaren often do not mean one specific summer. They are a standard idiomatic way to talk about the season generally.

So på sommaren is best understood as a fixed expression meaning in summer.

Here, så means so in the sense of therefore / as a result.

The sentence structure is:

• Öppettiderna ändras på sommaren = The opening hours change in summer
• så kontrollera hemsidan först = so check the website first

So så connects the two ideas:
because the opening hours change in summer, you should check the website first.

Kontrollera is the imperative form, used for commands or instructions.

So:

• kontrollera! = check!
• läs! = read!
• vänta! = wait!

In this sentence, it is giving practical advice or an instruction:

• kontrollera hemsidan först = check the website first

Swedish imperatives are often the same as the verb stem or infinitive-looking form, depending on the verb.

Yes, it works well here. Kontrollera is common when you mean check/verify information.

Another possible verb is kolla, which is more informal:

• kontrollera hemsidan först = more neutral/formal
• kolla hemsidan först = more conversational

Because this sounds like a notice or public information, kontrollera is a very suitable choice.

Because kontrollera takes a direct object here.

• kontrollera hemsidan = check the website

You are checking the website itself, meaning you are consulting it for information.

If you said på hemsidan, that would suggest a different structure, such as:

• kontrollera informationen på hemsidan = check the information on the website

So in the original sentence, hemsidan is simply the object of the verb.

Hemsidan means the website.

Swedish often uses the definite form when the specific thing is understood from context. If this sentence appears on a sign, in a message, or on a business page, it is obvious which website is meant: our website / the relevant website.

So:

• hemsida = a website
• hemsidan = the website

Först means first.

So kontrollera hemsidan först means:

• check the website first

It implies: do this before you come, visit, or rely on the listed hours.

It is about order: first check the website, then make your plans.

Good question. In this sentence, så is functioning more like so/therefore, linking two main clauses. The second part is effectively an instruction:

• Öppettiderna ändras på sommaren, så kontrollera hemsidan först.

With an imperative like kontrollera, there is no subject written out, so there is no visible inversion issue.

If you used a full clause with a subject, word order could look different depending on structure. For example:

• Öppettiderna ändras på sommaren, så du bör kontrollera hemsidan först.
  = The opening hours change in summer, so you should check the website first.

That sounds natural too.

Not by itself. Innan means before, but it normally needs something after it, or the sentence needs to make the timing clearer.

For example:

• Kontrollera hemsidan innan du åker dit. = Check the website before you go there.
• Kontrollera hemsidan först. = Check the website first.

In the original sentence, först is shorter and more natural for a general instruction.

It is mostly neutral.

• öppettiderna ändras sounds like standard public information
• kontrollera hemsidan först is clear and practical
• it is neither very casual nor especially formal

This is exactly the kind of sentence you might see on a sign, a business webpage, or an automated message.

A more conversational version might be:

• Öppettiderna ändras på sommaren, så kolla hemsidan först.

Here, kolla is more informal than kontrollera.

The original version is still very natural, but slightly more polished or official.

Yes:

• Öppettiderna = the opening hours
• ändras = change / are changed
• på sommaren = in summer / during the summer
• så = so / therefore
• kontrollera = check
• hemsidan = the website
• först = first

So the overall structure is:

The opening hours change in summer, so check the website first.