Сегодня чай горячее, чем обычно.

In Russian, the present-tense form of to be is usually omitted.

So Сегодня чай горячее, чем обычно literally looks like:

Today tea hotter than usual.

That is completely normal Russian. In the past or future, Russian would use быть:

• Вчера чай был горячее, чем обычно.
• Завтра чай будет горячее, чем обычно.

But in the present tense, no is is needed.

Чай is the subject of the sentence, so it stays in the nominative.

The basic structure is:

• чай = the tea
• горячее = hotter
• чем обычно = than usual

So the sentence is built around the tea being the thing described.

Here горячее is the simple comparative form of горячий.

• горячий = hot
• горячее = hotter

So this is the Russian equivalent of an English -er comparative, as in hot → hotter.

In this sentence, горячее means hotter, not hot.

Because this is a comparative form, and simple comparatives in Russian usually do not agree in gender, number, or case with the noun.

So even though чай is masculine, you still say:

• чай горячее
• кофе горячее
• суп горячее

The comparative form stays the same.

This is different from a normal adjective like горячий, which would agree:

• горячий чай
• горячий суп

Чем means than in comparisons.

So:

• горячее, чем обычно = hotter than usual

It introduces the second part of the comparison, just like English than.

Because обычно here is an adverb, meaning usually or as usual.

The phrase чем обычно really means something like:

• than it usually is
• than usual

Russian often leaves out words that are understood from context. So the full idea is shorter than it would be in English.

You are not comparing the tea to a noun like a usual tea. You are comparing today’s tea to its usual state.

These forms do different jobs:

• горячий = an adjective, hot
  • горячий чай = hot tea
• горячо = usually an adverb or predicative word, hot
  • Мне горячо = I feel hot
  • Здесь горячо = It’s hot here
• горячее = comparative, hotter
  • Чай горячее = The tea is hotter

So in your sentence, горячее is the comparative form, not the adverb горячо.

Yes, you could say более горячий, but горячее is more natural here.

Compare:

• Сегодня чай горячее, чем обычно. = the most natural everyday version
• Сегодня чай более горячий, чем обычно. = grammatical, but heavier and less conversational

Russian often prefers the simple comparative form when it exists.

Because in standard Russian spelling, a comparison introduced by чем is normally separated by a comma.

So:

• Сегодня чай горячее, чем обычно.

That comma is standard and expected here.

No, Russian word order is fairly flexible. The sentence can be rearranged, but the emphasis changes.

For example:

• Сегодня чай горячее, чем обычно. = emphasis on today
• Чай сегодня горячее, чем обычно. = emphasis on the tea

Both are natural. The original version puts Сегодня first, so it foregrounds the time.

Yes. That is also correct and very natural.

• Сегодня чай горячее, чем обычно.
• Сегодня чай горячее обычного.

Both can mean The tea is hotter today than usual.

The difference is slight:

• чем обычно = than it usually is
• обычного = than normal / than the usual level

Both are common, and learners should understand both patterns.