- Seasons (inner → outer: older → newer)
- Peak week of the season
- COVID-19 period (influenza almost absent)
- Season in progress (unfinished, no peak mark)
- Gaps are not joined
Northern hemisphere: starts at ISO week 27 (early July), July at the topSouthern hemisphere: starts at ISO week 1 (early January), January at the top
Data: WHO FluNet (GISRS laboratories), summed over sample origins per country-week, each season normalised to its maximum. Testing volumes differ between countries, so compare shapes, not heights. The outermost ring is the season still in progress as of Oct 26, 2026: it is scaled to the typical peak of the three previous full seasons, carries no peak mark and is left out of the median peak week, as are the COVID-19-period seasons.
Japan's FluNet records lack total specimens tested, so detections rather than positivity are used for every country here.
Seasonal peak week by country (text alternative)
| Country | Seasons | Median peak week | Hemisphere |
|---|---|---|---|
| Australia | 14 | 34 (Aug) | S |
| Brazil | 14 | 20 (May) | S |
| China | 15 | 2 (Jan) | N |
| France | 15 | 6 (Feb) | N |
| Germany | 14 | 6 (Feb) | N |
| India | 15 | 34 (Aug) | N |
| Japan | 13 | 3 (Jan) | N |
| Russia | 14 | 8 (Feb) | N |
| South Africa | 14 | 24 (Jun) | S |
| South Korea | 13 | 3 (Jan) | N |
| United States | 15 | 4 (Jan) | N |