Wakati wa joto, mimi ninapendelea shati nyembamba kuliko koti zito.

The wa is a connector meaning of. In Swahili, this connector changes form depending on the noun class of the first noun.

Here:

• wakati = time/period
• wa = of
• joto = heat

So wakati wa joto = time of heat.

This kind of structure is very common in Swahili:

• kikombe cha chai = cup of tea
• kitabu cha mwanafunzi = student’s book / book of the student
• wakati wa mvua = rainy season / time of rain

Good question. In Swahili, the verb already includes the subject:

• ni- = I
• -napendelea = prefer / am preferring

So ninapendelea already means I prefer.

The separate pronoun mimi is often added for:

• emphasis
• contrast
• clarity

So:

• Ninapendelea shati nyembamba... = I prefer a thin shirt...
• Mimi ninapendelea shati nyembamba... = I, for my part, prefer a thin shirt...

It is grammatical with or without mimi, but with mimi it can sound a little more emphatic.

Ninapendelea can be broken down like this:

• ni- = I
• -na- = present tense marker
• -penda = like/love
• -lea / -elea here forms pendelea, which means prefer

So ninapendelea = I prefer / I am preferring.

In practice, you should learn kupendelea as the verb to prefer.

Examples:

• Ninapendelea chai. = I prefer tea.
• Tunapendelea kutembea. = We prefer to walk.

Kuliko means than in comparisons.

So:

• shati nyembamba kuliko koti zito = a thin shirt rather than / more than a heavy coat

It is used when comparing two things:

• Asha ni mrefu kuliko Juma. = Asha is taller than Juma.
• Napenda chai kuliko kahawa. = I like tea more than coffee.

In this sentence, it marks what is being preferred:

• I prefer a thin shirt than a heavy coat More natural English would be:
• I prefer a thin shirt to a heavy coat

In Swahili, adjectives usually come after the noun they describe.

So:

• shati nyembamba = thin shirt
• koti zito = heavy coat

This is the normal word order:

• noun + adjective

More examples:

• mtoto mdogo = small child
• nyumba kubwa = big house
• kitabu kizuri = good book

Swahili adjectives often agree with the noun class of the noun they describe.

Here:

• shati takes nyembamba
• koti takes zito

The adjective for heavy comes from -zito, and it changes to match the noun class:

• mzigo mzito = heavy load
• jiwe zito = heavy stone
• koti zito = heavy coat

Not every adjective changes in the same way. Some, like nyembamba (thin/narrow/lightweight), often stay the same in form. Others show clearer agreement.

So the difference is due to noun-class agreement and the fact that different adjectives behave differently.

It can mean several related things depending on context:

• thin
• slim
• narrow

With clothing, shati nyembamba usually means a thin/light shirt, meaning a shirt made of lighter material or better for hot weather.

So in this sentence, thin/light shirt is the best interpretation.

Yes. Koti is often used for coat and can also refer to a jacket, depending on context.

If the meaning shown to the learner is coat, that fits very well here, especially because it is contrasted with hot weather and a thin shirt. The important idea is a heavier outer garment.

No. It is a good and natural expression, but there are other ways to express a similar idea, depending on context.

For example:

• Wakati wa joto = during hot weather / in the hot season
• Kunapokuwa na joto = when it is hot
• Katika hali ya hewa ya joto = in hot weather / in a hot climate

The sentence given is nice because it is short and natural for learners.

Yes. The comma is not essential for understanding.

You can write:

• Wakati wa joto mimi ninapendelea shati nyembamba kuliko koti zito.

The comma simply helps show that wakati wa joto is an introductory time phrase, similar to English:

• In hot weather, I prefer...

It normally expresses a general preference.

Because of:

• the present tense ninapendelea
• the general time expression wakati wa joto

it means something like:

• When it’s hot, I prefer a thin shirt to a heavy coat

So it sounds like a usual habit or preference, not just one single occasion.

Yes, in this sentence rather than can sound more natural in English.

So:

• mimi ninapendelea shati nyembamba kuliko koti zito

can be translated as:

• I prefer a thin shirt to a heavy coat
• I prefer a thin shirt rather than a heavy coat

Even though kuliko is often taught as than, the best English translation depends on the whole sentence.

The structure is:

• Wakati wa joto = time expression
• mimi = subject pronoun for emphasis
• ninapendelea = verb
• shati nyembamba = object
• kuliko koti zito = comparison phrase

So the overall order is:

Time expression + subject + verb + object + comparison

That gives: Wakati wa joto, mimi ninapendelea shati nyembamba kuliko koti zito.

A simpler version would be:

• Wakati wa joto, ninapendelea shati nyembamba kuliko koti zito.

This removes mimi, because the verb already shows I.

You could also say:

• Ninapendelea shati nyembamba wakati wa joto. = I prefer a thin shirt in hot weather.

That version is also understandable, but the original sentence puts the time phrase first for emphasis.