Halijoto imeongezeka.

The verb has to agree with the noun halijoto.

In imeongezeka:

• i- = the subject marker agreeing with halijoto
• -me- = perfect marker, often meaning has
• -ongezeka = increase / go up (intransitive)

So Halijoto imeongezeka literally works like Temperature it-has-increased.

A native English speaker often expects one verb form for everything, but in Swahili the beginning of the verb changes depending on the noun class of the subject.

-me- usually marks the perfect tense/aspect. In many contexts, it is best translated as:

• has increased
• has gone up
• increased (with present relevance)

So:

• imeongezeka = has increased

Compare:

• inaongezeka = is increasing / increases
• itaongezeka = will increase
• iliongezeka = increased (past)

So this sentence suggests the increase has already happened.

This is a very common learner question.

• imeongezeka = has increased
  The change is already completed, or is being presented as an accomplished fact.

• inaongezeka = is increasing
  The change is ongoing right now, or happens generally.

So:

• Halijoto imeongezeka = The temperature has increased.
• Halijoto inaongezeka = The temperature is increasing.

For learners, the safest approach is to treat halijoto as a single vocabulary item meaning temperature.

You may notice it looks like hali + joto, and that can help you remember it, but in normal use it functions as one noun: halijoto.

So in this sentence, just learn:

• halijoto = temperature

Here it is singular: temperature.

In practice, halijoto is usually used like a singular mass/abstract noun, since people normally talk about the temperature rather than temperatures in everyday sentences like this.

That is why the verb uses the singular agreement form i- in imeongezeka.

This is an important distinction:

• kuongezeka = to increase / to go up
  This is intransitive: the subject itself becomes greater.

• kuongeza = to increase something / add
  This is transitive: someone causes something else to become greater.

Examples:

• Halijoto imeongezeka. = The temperature has increased.
• Ameongeza halijoto. = He/She has increased the temperature.

So in your sentence, -ongezeka is used because the temperature itself is going up.

Swahili does not normally use articles like a, an, and the.

So Halijoto imeongezeka can naturally mean:

• The temperature has increased
• Temperature has increased

In English, the is usually required here, but in Swahili it is simply not expressed as a separate word.

A helpful pronunciation guide is:

• ha-li-JO-to
• i-me-o-nge-ZE-ka

A few key points:

• Swahili words are usually stressed on the second-to-last syllable
• Every vowel is pronounced clearly
• In imeongezeka, the e and o are both heard: i-me-o-..., not merged into one English-style sound

So try:

ha-li-JO-to i-me-o-nge-ZE-ka

Yes, Halijoto imeongezeka is perfectly natural and correct.

It can sound a bit more neutral or slightly technical because halijoto means temperature.

In everyday speech, especially when talking about weather, people might also say:

• Joto limeongezeka. = The heat has increased.

The difference is roughly:

• halijoto = temperature
• joto = heat / warmth

So if you specifically mean measured temperature, halijoto imeongezeka is a very good choice.

No. In halijoto, the ha- is just part of the noun.

This can confuse learners because ha- is also used in Swahili negative verb forms, for example:

• haongezeki = it does not increase

But in halijoto, there is no negation. The sentence is positive:

• Halijoto imeongezeka = The temperature has increased.