Eu chego a casa ao meio-dia.

You can drop "Eu".

Portuguese is a “pro‑drop” language: the verb ending already tells you who the subject is.

• Chego a casa ao meio‑dia. – perfectly natural
• Eu chego a casa ao meio‑dia. – also correct, but adds emphasis on I (“I arrive home at noon,” as opposed to someone else)

"Chegar" is the infinitive (“to arrive”).
In a full sentence with a subject, you normally need a conjugated form.

Present tense of chegar (to arrive):

• eu chego – I arrive
• tu chegas – you arrive (informal singular)
• ele/ela chega – he/she arrives
• nós chegamos – we arrive
• vocês/eles/elas chegam – you (pl.) / they arrive

So "Eu chego" = “I arrive.”

Because chegar (to arrive) in European Portuguese normally uses the preposition a to introduce the place you arrive at:

• chegar a casa – to arrive home
• chegar à escola – to arrive at school
• chegar ao trabalho – to arrive at work

By contrast, em casa means “at home” (location, not movement):

• Estou em casa. – I am at home.
• Vou estar em casa ao meio‑dia. – I will be at home at noon.

So:

• chegar a casa – motion towards home / moment of arrival
• estar em casa – being at home

Visually they’re similar, but they’re not the same:

• a casa (no accent) = preposition "a" + noun "casa" with no article

  • In practice, this usually means “(to) home” in general.
  • Chego a casa. – I arrive home.

• à casa (with accent grave) = contraction of a + a = à (“to the”)

  • à = “to the” (feminine singular).
  • Vou à casa do João. – I go to João’s house.

So:

• chego a casa – I arrive home (my home / home in general)
• chego à casa do vizinho – I arrive at the neighbour’s house

Both can occur, but they’re used with different verbs and nuances:

• chegar a casa – standard with chegar in European Portuguese

  • Focus: the point of arrival.
  • Chego a casa ao meio‑dia. – I arrive home at noon.

• ir / voltar / vir para casa – often with para to express destination/goal

  • Vou para casa. – I’m going home.
  • Volto para casa. – I come back home.

With chegar, the natural option in European Portuguese is a casa, not para casa.

In European Portuguese, no – that sounds wrong or foreign.
The standard pattern is:

• chegar a
  • place
    
    • chegar a casa
    • chegar ao aeroporto
    • chegar à universidade

In Brazilian Portuguese, people very often say chegar em casa, but that’s regional/informal and not the European norm. If you’re aiming for Portuguese from Portugal, use chegar a casa.

"Ao" is a contraction:

• a + o → ao

Literally: “at the” / “to the” (masculine singular).

With time expressions, Portuguese normally uses a:

• ao meio‑dia – at noon
• às duas (horas) – at two o’clock (a + as → às)
• à uma (hora) – at one o’clock (a + a → à)

So ao meio‑dia literally: “at the midday.”

For clock time, Portuguese uses a (→ ao / à / às), not em (→ no / na / nos / nas):

• ao meio‑dia – at noon
• às três – at three o’clock
• à uma – at one

No meio‑dia would sound wrong in this sense.
Em is used more for general location/time period, not a precise clock time:

• no verão – in summer
• no domingo – on Sunday (more common in PT: ao domingo for habitual action)

Yes.

Portuguese simple present is flexible:

1. Habitual / routine

   • Eu chego a casa ao meio‑dia.
     = I (generally) arrive home at noon (e.g. every day after work).

2. Future (scheduled / planned)

   • If said in a specific context, it can mean
     “I will arrive home at noon (tomorrow/that day).”

The exact meaning depends on context and sometimes adverbs:

• Normalmente chego a casa ao meio‑dia. – normally I arrive home at noon.
• Amanhã chego a casa ao meio‑dia. – tomorrow I’ll arrive home at noon.

Approximate pronunciation (Lisbon‑type accent):

• chego – [ʃe‑gu], roughly like “SHEH-goo”
• a – usually very weak, almost attached to the next word
• casa – [KA‑zɐ], like “KAH-zuh” (last vowel very reduced)
• ao – [aw], like English “ow” in cow, but shorter
• meio‑dia – [MAY‑oo DEE‑ə], with meio sounding like “MAY‑oo”

Said together, quite fast and with reductions:

[ˈʃe.ɡu ɐ ˈka.zɐ aw ˌmɐj.u ˈdi.ɐ]

You don’t need to master the IPA; just aim for:

"SHEH-goo a KAH-zuh ow MAY-oo DEE-uh"

Under the current spelling rules:

• meio‑dia (with hyphen) = the noun “midday / noon”
• meio dia (without hyphen) would mean literally “half a day” (quantity), and is rare.

So in "ao meio‑dia", meio‑dia is a fixed noun (“midday / noon”), and it keeps the hyphen.

Normally, yes:

• ao meio‑dia – at 12:00 (midday / noon)

It can also be used a bit more loosely as “around midday” in casual speech, but in time expressions like this, it is usually understood as twelve o’clock sharp.

For comparison:

• meio‑dia – midday / noon (12:00)
• meia‑noite – midnight (00:00)

It’s grammatically possible but not the same:

• chegar a casa – emphasizes the moment of arrival

  • Chego a casa ao meio‑dia. – I arrive home at noon.

• vir para casa / vir a casa – emphasizes coming (towards here/home)

  • Venho para casa ao meio‑dia. – I (will) come home at noon.

In practice, to express a routine arrival time, chegar a casa is the most natural in European Portuguese.