What it means
あまりにも means “too much” or “excessively” and emphasizes that a degree is far beyond what is appropriate, expected, or manageable. It commonly comes before an adjective or a predicate that describes an excessive state. With verbs, it is more natural when accompanied by an expression showing the excessive degree, such as ～すぎる or a phrase like 長時間. The expression can be used in both familiar and polite sentences; the register is determined by the rest of the sentence.
Usage note
あまりにも should not be treated as a freely natural intensifier before every verb. A bare verb after it can sound incomplete, so verbs usually appear with ～すぎる, a degree expression, or a clear result or consequence.
How to use it
この通りはあまりにも静かです。
This street is far too quiet.
この荷物はあまりにも重いです。
This luggage is far too heavy.
彼はあまりにも長時間働きました。
He worked for far too long.
この通りはあまりにも静かだ。
This street is far too quiet.
この荷物はあまりにも重い。
This luggage is far too heavy.
彼はあまりにも長時間働いた。
He worked for far too long.
Example sentences
この部屋はあまりにも静かで、時計の音まで聞こえます。
This room is so quiet that I can even hear the sound of the clock.
あまりにも重い荷物だったので、一人では運べませんでした。
Because the luggage was too heavy, I could not carry it alone.
あまりにも複雑な説明だったので、誰もすぐには理解できませんでした。
The explanation was so complicated that no one could understand it right away.