急に(きゅうに) — Suddenly / All of a sudden

• 急に雨が降り始めた。

  Kyuu ni ame ga furihajimeta.

  It suddenly started raining.

  急に + 降り始めた (started to fall) = suddenly began

• 仕事中に急に電話が鳴った。

  Shigoto chuu ni kyuu ni denwa ga natta.

  The phone suddenly rang while I was working.

  急に + 鳴った = unexpected interruption

• 急に寒くなった。

  Kyuu ni samuku natta.

  It suddenly got cold.

  急に + 寒くなった (became cold)

• ・急に vs 突然 vs いきなり — all mean 'suddenly.'
• ・急に = suddenly/abruptly (a change of state or event), neutral and very common.
• ・突然 = all of a sudden (surprising events, slightly more formal/dramatic).
• ・いきなり = out of nowhere (very abrupt, often with no warning, sometimes negative: いきなり怒った = got angry out of nowhere).

Commonly confused with

The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones 急に is tested against.

• あまり〜ない — Not very / Not much
• ばかり — Nothing but / Only
• きっと — Surely / Certainly / I'm sure
• そんなに — That much / To that extent
• 全然 (ぜんぜん) — Absolutely not / Not at all / (casual: totally)
• たとえば — For example / For instance
• とうとう — Finally / At last / In the end
• まず — First / First of all / To begin with