لما طلعت من المحطة، كان فيه مطر وهوا.

Here لما means when.

It introduces a time clause: لما طلعت من المحطة = when I came out of the station.

In Egyptian Arabic, لما is very common for talking about something that happened and what was happening at that time. Depending on context, it can sometimes feel like when, once, or after, but in this sentence when is the most natural meaning.

Because the verb already includes the subject.

طلعت means I went out / I came out / I left, and the ending -ت shows I in the past tense.

So Egyptian Arabic often does not need a separate subject pronoun unless you want extra emphasis.
You could say أنا طلعت for emphasis, but normally just طلعت is enough.

All of those are possible in different contexts.

The verb طلع has a broad range of meanings, including:

• go up
• come out
• appear
• leave / head out

In this sentence, because it is followed by من المحطة meaning from the station, the natural sense is came out of or left the station.

So طلعت من المحطة is best understood as I came out of the station.

المحطة means the station or sometimes the stop, depending on context.

It can refer to things like:

• a train station
• a metro station
• a bus station
• a stop or terminal

So the exact English translation depends on the situation, but the station is a good general translation here.

من means from.

So من المحطة means from the station.

This matches the idea of moving out of a place:

• طلعت من البيت = I came out of the house
• خرجت من العربية = I got out of the car
• طلعت من المحطة = I came out of the station

It marks the starting point of the movement.

This is a very common Egyptian Arabic structure.

• فيه can mean there is / there are
• كان فيه means there was / there were

So:

• فيه مطر = there is rain
• كان فيه مطر = there was rain

In this sentence, كان فيه مطر وهوا means there was rain and wind.

A learner may notice that فيه can also literally mean something like in him/it in other contexts, but here it functions as part of an existential expression, meaning there is/there are.

Because كان فيه works as an existential pattern, basically there was / there were.

In everyday Egyptian Arabic, كان فيه is very often used as a fixed expression, and كان commonly stays in the singular masculine form even if what follows is plural or includes more than one thing.

So كان فيه مطر وهوا is perfectly natural.

This is different from thinking of مطر وهوا as the main grammatical subject in the English way. The sentence is built more like there was rain and wind, not rain and wind were.

Here هوا most naturally means wind or air, and in this sentence the idea is basically that it was windy.

So مطر وهوا gives a weather description: rain and wind.

Depending on context, هوا can mean:

• air
• wind
• breeze

In weather sentences like this one, wind is the best choice.

Because Arabic does not have an indefinite article like English a or an.

So:

• مطر = rain
• هوا = wind / air

You do not need a separate word for a.

Also, these are mass nouns in this context, so English itself often does not use a either. We normally say there was rain and wind, not there was a rain and a wind.

Because المحطة is definite: the station.

The prefix ال is the Arabic definite article, equivalent to English the.

So:

• المحطة = the station
• محطة = a station / station

But مطر and هوا are indefinite here and are being mentioned generally, so they appear without ال.

Yes, very natural.

Instead of using weather adjectives the way English often does, Egyptian Arabic frequently uses nouns in an existential structure:

• فيه مطر = it is raining / there is rain
• فيه هوا = it is windy / there is wind
• كان فيه مطر وهوا = there was rain and wind

So this sentence sounds like normal everyday Egyptian Arabic, not a word-for-word translation from English.

A common pronunciation would be:

lamma ṭiliʿt men el-maḥaṭṭa, kān fīh maṭar wi hawa

A few helpful notes:

• لما = lamma
• طلعت is often pronounced ṭiliʿt
• من is often heard as men in connected speech
• المحطة = el-maḥaṭṭa
• و before a consonant is often pronounced wi, so وهوا sounds like wi hawa

Two sounds that may feel new to English speakers:

• ح in المحطة is a strong breathy h
• ع in طلعت is a throat sound that has no exact English equivalent

Also, the طّ in محطة is doubled, so it is held a little longer than a single ط.