Flu season usually hits in the colder months, but the exact timing depends on where you live and the year. In many places, it’s more accurate to think of a “flu period” that can stretch over several months rather than a single start and end date.

Quick Scoop: When’s flu season?

  • In the Northern Hemisphere (U.S., Canada, most of Europe), flu season typically runs from about October through April or May.
  • In the U.S. , health agencies often describe flu season as fall through spring , with most activity from October to May and a peak between December and February , though significant activity can last into March or even May.
  • In the Southern Hemisphere (Australia, South Africa, parts of South America), flu season is roughly the opposite months , often April/May through October , peaking in their winter (around July–August).
  • Flu can circulate all year , but the risk is highest and outbreaks are most visible during these colder, drier months.

Why it’s a bit unpredictable now

Recent years (especially after the COVID‑19 pandemic) have made flu timing less predictable. Some seasons have:

  • Earlier peaks (as early as November).
  • Later peaks (even into April or beyond).
  • Multiple peaks in a single season.

Because of this, public health experts emphasize getting your flu shot before activity really ramps up—typically early fall in the Northern Hemisphere, or before local winter in the Southern Hemisphere.

A good rule of thumb:
Think “flu season” as fall–spring in the north and winter months in the south, with the worst of it clustering around mid‑winter.

TL;DR:

  • Northern Hemisphere: about October–April/May , peak December–February.
  • Southern Hemisphere: roughly April/May–October , peak in mid‑winter (often July–August).

Information gathered from public forums or data available on the internet and portrayed here.