اليوم مشمس.

In Arabic, the verb to be is usually not written in the present tense.

So:

• اليوم مشمس = Today is sunny

This kind of sentence is called a nominal sentence. It is made of:

• a topic/subject: اليوم
• a predicate: مشمس

If you wanted was, will be, etc., then Arabic would use a verb such as:

• كان اليوم مشمسًا = The day was sunny / Today was sunny
• سيكون اليوم مشمسًا = Today will be sunny

It can mean either, depending on context.

In this sentence, اليوم means today.

Literally, the word is built from:

• ال = the
• يوم = day

So the literal form is the day, but very often اليوم is simply the normal Arabic word for today.

Because the usual word for today is اليوم.

Even though الـ often means the, you should learn اليوم as a complete, very common word meaning today in many contexts.

So in this sentence, don’t over-translate it as the day. Just understand it as today.

مشمس means sunny.

It comes from the root ش م س, which is related to the sun:

• شمس = sun

So مشمس has the sense of sun-filled or sunny.

Because in this sentence مشمس is the predicate adjective, not a noun being made definite.

In simple terms:

• اليوم = the topic: today
• مشمس = what is being said about it: sunny

In Arabic nominal sentences, the predicate is often indefinite, so مشمس appears without الـ.

That is normal.

Yes. It is a complete and correct sentence.

Arabic often expresses simple present-tense statements very compactly. A two-word sentence like this is perfectly normal:

• اليوم مشمس = Today is sunny

Arabic does not need an extra word for is here.

In a basic textbook analysis:

• اليوم = the subject/topic (mubtadaʾ)
• مشمس = the predicate (khabar)

So the sentence structure is:

• Today
  • sunny

or more naturally in English:

• Today is sunny

A simple learner-friendly pronunciation is:

• al-yawmu mushmis

A rough English guide:

• al-yawm: sounds like al-yowm
• mushmis: roughly moosh-mis

More exactly, with full case endings in careful Arabic, it is often read as:

• اليومُ مُشْمِسٌ

But in normal writing, the short vowels are usually not written.

Because normal Arabic writing usually leaves out short vowels and most other diacritics.

So you see:

• اليوم مشمس

But a fully vowelled version would be:

• اليومُ مُشْمِسٌ

Arabic readers normally figure out the vowels from:

• vocabulary
• grammar
• context

This is one of the main things beginners need time to get used to.

In a fully vocalized, textbook-style reading, you will often see:

• اليومُ مُشْمِسٌ

That means:

• اليومُ is nominative
• مُشْمِسٌ is also nominative

That is because in a basic nominal sentence, both the mubtadaʾ and the khabar are in the nominative case.

In everyday writing and speech, these endings are often not written or not fully pronounced.

Yes, as a predicate adjective it appears in the appropriate form.

Here, اليوم is grammatically masculine singular, so مشمس is also masculine singular.

If the thing described were feminine, the adjective would usually change too. For example, a feminine form would be:

• مشمسة

So agreement is an important part of Arabic grammar.

Yes, it is a good and clear Modern Standard Arabic sentence.

You may also hear or see other natural versions, such as:

• الجو مشمس اليوم = The weather is sunny today
• الجو اليوم مشمس = The weather today is sunny

These are also very common, especially because they mention the weather directly.

But اليوم مشمس is still a valid and useful sentence for learners.

It is mainly used for weather, days, skies, and places that are sunny.

For example:

• يوم مشمس = a sunny day
• طقس مشمس = sunny weather
• سماء مشمسة is possible in meaning, though other expressions may also be used depending on style

So in اليوم مشمس, it is describing the day as sunny.

In Modern Standard Arabic, a common way is:

• اليوم ليس مشمسًا = Today is not sunny

Here:

• ليس = is not

Notice that when ليس is used, the predicate is typically in the accusative, so مشمس becomes مشمسًا in full vocalization.

In less formal varieties of Arabic, you may hear different negation patterns, but for MSA ليس is the standard choice.

You can simply add a question marker such as هل:

• هل اليوم مشمس؟ = Is today sunny?

You can also rely on intonation in some contexts, but هل is the standard clear way in MSA to form a yes/no question.

So:

• statement: اليوم مشمس
• question: هل اليوم مشمس؟