# El Niño impact on North American fall foliage

> Situation record from CLSTR: https://clstr.news/situations/el-nio-impact-on-north-american-fall-foliage
> Updated: 2026-09-30T08:00:21.000Z. Sources: 6. Developments: 2.

A strengthening El Niño climate pattern, described by some experts as a ‘Super El Nino’, is expected to influence the timing and quality of fall foliage in parts of North America.

In the Chicago region, scientists at The Morton Arboretum suggest that warmer-than-average temperatures could delay the onset of autumn colors. While higher precipitation has recently offset some drought effects, the color season may become compressed, with leaves changing rapidly once freezing temperatures arrive. 

Similarly, in Ontario, experts anticipate that warmer autumn temperatures may delay the appearance of vibrant pigments. However, because trees have not faced the same level of heat and rainfall stress as in previous years, the color progression could potentially be prolonged and more vivid.

## Timeline

### 2026-09-30: Ontario fall foliage may be delayed by ‘Super El Nino’

The strong ‘Super El Nino’ climate pattern may delay or prolong Ontario’s fall foliage due to warmer-than-normal autumn temperatures.

4 sources. https://clstr.news/cluster/ontario-fall-foliage-may-be-delayed-by-super-el-nino

### 2026-09-22: El Niño may delay and compress fall foliage in Chicago area

A record-breaking El Niño may delay and compress the fall foliage season in the Chicago area due to forecasted warmer-than-average temperatures through late autumn.

2 sources. https://clstr.news/cluster/el-nio-may-delay-and-compress-fall-foliage-in-chicago-area

---
Cite as: El Niño impact on North American fall foliage. CLSTR, https://clstr.news/situations/el-nio-impact-on-north-american-fall-foliage