Learn Portuguese (Portugal): O calor em agosto é muito forte.

In Portuguese, months of the year like agosto (August), days of the week, and seasons are not capitalized unless they appear at the beginning of a sentence.

Why do we use em instead of no before agosto?

In European Portuguese, months generally don't take a definite article (o or a). Therefore, we just use the simple preposition em (in) rather than no (which is em + o).

Weather is often temporary, so why use é (from ser) instead of está (from estar)?

While you would use estar to describe how the weather is right now (like está calor - it is hot), this sentence makes a general, permanent statement about what August is always like. For facts and permanent characteristics, we use the verb ser (é).

Does the adjective forte change if it describes a feminine noun?

No, adjectives that end in -e, like forte (strong) or quente (hot), do not change for gender. They take the exact same form for both masculine and feminine nouns. They only add an -s if the noun is plural.

Why doesn't change its ending here?