Cook Islands in September

September is Cook Islands's best month (rank 1 of 12): its 3 destinations average 86/100, led by Aitutaki at 86 — 26°C and 12 rainy days — while Rarotonga trails at 85 with 83 mm of rain.

#1 of 12 months for Cook Islands · 3 destinations · updated September 2026 · climate normals from ERA5 reanalysis

Cook Islands, month by month

86/100 in September
  1. 75Jan
  2. 73Feb
  3. 77Mar
  4. 79Apr
  5. 73May
  6. 83Jun
  7. 81Jul
  8. 83Aug
  9. 86Sep
  10. 84Oct
  11. 85Nov
  12. 76Dec

Where in Cook Islands in September

#PlaceTypeFeels-like highRainComfortAt its best
1AitutakiIsland26°C72 mm · 12 days86 tier AYes
2AvaruaIsland27°C83 mm · 10 days86 tier AYes
3RarotongaIsland25°C83 mm · 10 days85 tier AYes

Comfort is SeasonMap's 0–100 score; each place is judged through the lens that suits it — beaches on beach weather, ski resorts on snow. "At its best" means September is one of that place's own top three months. Feels-like highs fold in humidity, wind and sun.

What's on in Cook Islands in September

  • Humpback whale season · Aitutaki and 2 more places · 15 Jul – 15 Oct (usually)

Seasons in force

Dry season · 2 places

Other good months for Cook Islands

November · 85/100October · 84/100June · 83/100Weakest: May · 73/100
← Cook Islands in AugustCook Islands in October →Best time to visit Cook Islands, month by monthCompare: Aitutaki vs Avarua in September