Η πρόγνωση λέει ότι ο καύσωνας τελειώνει αύριο, αλλά η υγρασία θα μείνει.

Greek uses the definite article much more often than English does. In this sentence, all three nouns are specific and natural to present with the article:

• η πρόγνωση = the forecast
• ο καύσωνας = the heatwave
• η υγρασία = the humidity

A learner coming from English may expect fewer articles, but in Greek they are very common, especially with subjects of a sentence.

Also notice that the article changes to match the noun’s gender, number, and case:

• η for feminine singular nominative
• ο for masculine singular nominative

So:

• η πρόγνωση is feminine
• ο καύσωνας is masculine
• η υγρασία is feminine

λέει ότι literally means says that.

So the structure is:

• Η πρόγνωση λέει ότι...
• literally: The forecast says that...
• natural English: The forecast says that... / The forecast is saying that... / The forecast predicts that...

In Greek, it is very normal to use λέω (to say) in this way, even with things like forecasts, signs, instructions, or written information.

Examples:

• Η πινακίδα λέει... = The sign says...
• Το πρόγραμμα λέει... = The schedule says...

So Η πρόγνωση λέει ότι... is a very natural Greek way to introduce what the forecast predicts.

ότι means that and introduces a subordinate clause.

Here it connects the main clause to the content of what the forecast says:

• Η πρόγνωση λέει = The forecast says
• ότι ο καύσωνας τελειώνει αύριο = that the heatwave ends tomorrow

So ότι works just like English that in sentences such as:

• I think that...
• She says that...
• The forecast says that...

In everyday Greek, πως can sometimes be used in similar situations, but ότι is standard and completely correct here.

This is a very common and important Greek pattern.

τελειώνει is grammatically present tense, but Greek often uses the present tense for a scheduled, expected, or near-future event, especially when there is a time word like αύριο (tomorrow).

So:

• ο καύσωνας τελειώνει αύριο
• literally: the heatwave ends tomorrow
• natural meaning: the heatwave will end tomorrow

English can do this too:

• The semester ends tomorrow
• My flight leaves at 8

So Greek is not being strange here; it is using a pattern that English also uses.

Because Greek has more than one natural way to talk about the future.

In this sentence, the speaker uses:

• τελειώνει αύριο = present with future meaning
• θα μείνει = explicit future

Both are correct and natural.

The difference is not necessarily huge here. Often:

• present + future time word can sound immediate, scheduled, or straightforward
• θα + verb is the regular, explicit future form

So the sentence mixes two perfectly normal Greek future expressions:

• the heatwave ends tomorrow
• but the humidity will remain

This kind of variation is very common in real Greek.

θα μείνει is the future tense form of the verb μένω (to stay / remain).

It is made from:

• θα = future particle
• μείνει = the form used for the simple future here

So:

• μένω = I stay / remain
• θα μείνει = it will stay / remain

In this sentence, the subject is η υγρασία (the humidity), so θα μείνει means:

• the humidity will remain
• or more naturally, the humidity will stay

Notice that the stem changes from μεν- to μειν- in this form. That is normal for this verb.

This is because Greek verbs often use a different stem in the simple future and related forms.

For μένω:

• present: μένω, μένεις, μένει...
• simple future: θα μείνω, θα μείνεις, θα μείνει...

So the verb changes stem:

• μεν- in the present system
• μειν- in the simple future system

This is something learners just have to get used to, because many common verbs show stem changes.

Here are the relevant forms:

• μένει = it stays / it is staying
• θα μείνει = it will stay / remain

So η υγρασία θα μείνει is exactly what you would expect for the humidity will remain.

Yes. η υγρασία is the standard word for humidity or moisture, depending on context.

In weather language, it usually means humidity.

So in this sentence:

• η υγρασία θα μείνει means
• the humidity will remain

You may also hear it in other contexts:

• υγρασία στο δωμάτιο = humidity/dampness in the room
• πολλή υγρασία = a lot of humidity

So it is a useful word beyond weather forecasts too.

ο καύσωνας means heatwave.

It is a masculine noun, which is why it takes the masculine article ο.

Greek noun gender is grammatical, so it does not always follow any logic that feels obvious to an English speaker. You generally need to learn each noun together with its article:

• ο καύσωνας
• η πρόγνωση
• η υγρασία

That will help you remember both the meaning and the gender.

Also, the ending -ας is often a clue that a noun is masculine, though not every noun ending works the same way.

Yes, Greek word order is more flexible than English word order, because the endings and articles give extra grammatical information.

The sentence as written is very neutral and natural:

• Η πρόγνωση λέει ότι ο καύσωνας τελειώνει αύριο, αλλά η υγρασία θα μείνει.

But some movement is possible, especially for emphasis. For example:

• Η πρόγνωση λέει ότι αύριο ο καύσωνας τελειώνει...
• ...αλλά θα μείνει η υγρασία.

These versions can sound more marked or emphasize different parts.

For a learner, the original order is the best one to copy because it is clear, standard, and easy to process.

In most basic cases, yes. αλλά is the normal word for but.

Here it contrasts two ideas:

• the heatwave is ending tomorrow
• the humidity will remain

So αλλά is exactly the right connector.

It is very common and useful:

• Θέλω να έρθω, αλλά δεν μπορώ. = I want to come, but I can’t.

So in this sentence, it simply marks contrast.

A natural pronunciation guide would be something like:

• i PROG-no-see LE-i O-ti o KAF-so-nas te-LEE-o-ni AV-ri-o, a-LA i i-gra-SEE-a tha MEE-ni

A few useful stress points:

• πρόγνωση → stress on πρό-
• λέει → stress on λέ-
• καύσωνας → stress on καύ-
• τελειώνει → stress on -ώ-
• αύριο → stress on αύ-
• υγρασία → stress on -σί-
• μείνει → stress on μεί-

A few sound notes:

• γν in πρόγνωση may feel unfamiliar; just say it smoothly, roughly like gn in the middle of a word.
• υ in υγρασία sounds like ee in Modern Greek.
• αι in λέει and ει in μείνει are pronounced like ee.

Yes, you could.

• Η πρόγνωση λέει ότι... = The forecast says that...
• Η πρόγνωση προβλέπει ότι... = The forecast predicts that...

Both are correct, but they feel a little different:

• λέει is more everyday and conversational
• προβλέπει is a bit more formal or technical

So the original sentence sounds very natural in ordinary speech.

A very useful pattern here is:

• [Thing/source] λέει ότι [clause], αλλά [clause].

For example:

• Το δελτίο λέει ότι θα βρέξει, αλλά η θερμοκρασία θα μείνει υψηλή. = The bulletin says that it will rain, but the temperature will stay high.

Also notice these two future patterns you can reuse:

1. Present tense + future time word

   • φεύγω αύριο = I’m leaving tomorrow
   • τελειώνει αύριο = it ends tomorrow

2. θα + verb

   • θα μείνει = it will remain
   • θα βρέξει = it will rain

If you can recognize both patterns, sentences like this become much easier to understand.