Η πρόγνωση λέει ότι θα βρέχει όλη μέρα, οπότε δεν θα πάμε στο πάρκο.

Greek uses the definite article much more often than English. Here η πρόγνωση means the forecast.

Also, η tells you the noun is:

• feminine
• singular
• nominative (the subject of the sentence)

So Η πρόγνωση λέει... is literally The forecast says...

Λέει is the 3rd person singular present of λέω = to say.

So:

• λέω = I say
• λες = you say
• λέει = he/she/it says

Here the subject is η πρόγνωση, so Greek uses λέει: the forecast says.

Also, the Greek present tense often covers both:

• says
• is saying

In this sentence, says is the natural English translation.

Here ότι means that and introduces a clause:

• Η πρόγνωση λέει ότι...
• The forecast says that...

This is very common after verbs like:

• λέω = say
• νομίζω = think
• ξέρω = know

In everyday Greek, you will also often hear πως instead of ότι in this kind of sentence.

No. They are different:

• ότι = that
• ό,τι = whatever / anything that

So in this sentence, it must be ότι, because it introduces what the forecast says.

This is an aspect question, which is very important in Greek.

• θα βρέχει = it will be raining / it will rain continuously
• θα βρέξει = it will rain as a single whole event

Because the sentence says όλη μέρα = all day, Greek naturally prefers θα βρέχει, which emphasizes duration or ongoing action.

So:

• Θα βρέχει όλη μέρα = It will be raining all day
• Θα βρέξει αύριο = It will rain tomorrow

Both are possible in different contexts, but θα βρέχει fits better with all day.

Greek does not use a dummy subject like English it in weather expressions.

So:

• βρέχει = it rains / it’s raining
• χιονίζει = it snows / it’s snowing

There is no separate Greek word corresponding to English weather it here.

Greek often uses the accusative by itself to express duration of time.

So:

• όλη μέρα = all day
• όλη νύχτα = all night
• δύο ώρες = for two hours

You do not need a preposition like for here.

Also, Greek often allows both:

• όλη μέρα
• όλη τη μέρα

Both mean all day. The shorter version is very common.

Here οπότε means so, therefore, or as a result.

So:

• ..., οπότε δεν θα πάμε στο πάρκο.
• ..., so we won’t go to the park.

Be careful: οπότε can also mean when or whenever in other contexts. But in this sentence, it clearly means so / therefore.

In Modern Greek, negation comes before θα:

• δεν θα πάμε = we will not go

Not:

• θα δεν πάμε ❌

This word order is fixed. In speech and informal writing, you may also see δε θα instead of δεν θα.

Because Greek is a pro-drop language: the verb ending usually already tells you the subject.

Here πάμε means we go / let’s go / we will go depending on context, and the ending -με shows we.

So εμείς = we is usually omitted unless you want emphasis or contrast.

For example:

• Δεν θα πάμε = We won’t go
• Εμείς δεν θα πάμε = We won’t go (maybe others will)

After θα, Greek chooses between different aspect forms.

• θα πάμε = we will go (simple, one whole action)
• θα πηγαίνουμε = we will be going / we will go regularly

In this sentence, the meaning is a single future plan, so θα πάμε is the natural choice.

This is related to the Greek verb pair for go:

• πηγαίνω = imperfective
• πάω / πάμε = commonly used perfective/simple future form

So δεν θα πάμε στο πάρκο means we won’t go to the park, not we won’t be going there repeatedly.

Στο is a contraction of:

• σε + το = στο

So:

• στο πάρκο = to the park / in the park / at the park

The exact English translation depends on the verb. Because the verb here is πάμε = go, στο πάρκο means to the park.

Also:

• πάρκο is a neuter noun
• so the article is το
• and after σε, it becomes στο

So the full structure is:

• σε το πάρκο → στο πάρκο