{"id":30043,"date":"2024-10-11T11:45:54","date_gmt":"2024-10-11T15:45:54","guid":{"rendered":"https:\/\/www.purdue.edu\/fnr\/extension\/?p=30043"},"modified":"2025-02-13T15:44:06","modified_gmt":"2025-02-13T19:44:06","slug":"is-fall-foliage-due-to-seasonal-change-or-heat-waves","status":"publish","type":"post","link":"https:\/\/www.purdue.edu\/fnr\/extension\/is-fall-foliage-due-to-seasonal-change-or-heat-waves\/","title":{"rendered":"Is Fall Foliage due to Seasonal Change or Heat Waves?"},"content":{"rendered":"
\n

Purdue Agriculture News<\/a>: As autumn settles in, we eagerly await the transformation of leaves into vibrant hues of red, orange and yellow. However, this year might tell a different story due to prolonged periods of hot weather. Ben McCallister<\/a>, urban forestry specialist in Purdue University\u2019s\u00a0Department of Forestry and Natural Resources<\/a>, sheds light on what to expect this fall.<\/p>\n

The Impact of Weather on Fall Foliage Timing<\/strong>\"Ben<\/a><\/p>\n<\/div>\n

“Right now, we\u2019re seeing a mix of fall coming in and shifting temperatures, which is causing trees to respond. This back-and-forth hot weather is creating some color changes related to drought and stress. This can be expressed as brown color where leaves are starting to wilt and look a little crunchy from exposure to heat and drought stress,” McCallister explains.<\/p>\n

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While the typical color change occurs from mid-September to early November, it\u2019s not unusual for leaves to remain green at this point in the season. McCallister suggests that while the hot weather \u201cmost likely won\u2019t affect anything visually, it could influence fall foliage over time as climate change progresses.\u201d<\/p>\n

He anticipates a more pronounced display of fall colors extending through October, with some species showing their colors into November. Ultimately, the vibrancy and timing of these changes will depend on daily temperature fluctuations and the amount of sunlight trees receive.<\/p>\n

The environment also plays a significant role in how trees respond. For instance, urban areas with more concrete and buildings create a \u201curban heat island\u201d effect, which can delay color changes compared to more rural settings.<\/p>\n<\/div>\n

The Science Behind Color Transformation<\/strong><\/div>\n
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The science of fall foliage is both fascinating and complex. McCallister explains that different tree species respond to autumn at varying times, with chlorophyll being a key player in this process.<\/p>\n

“Changes in chlorophyll production leads to the color changes in leaves. Chlorophyll allows leaves to take up sunlight and convert it into energy, creating carbohydrates in the form of sugars \u2013 really anything that gives energy to the tree to help it grow, sustain itself and compartmentalize,\u201d McCallister notes.<\/p>\n

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\u00a0As temperatures cool and the sunlight diminishes, chlorophyll production declines, allowing the green hues of leaves to fade. This decline reveals carotenoids and anthocyanins \u2013 two chemicals essential to fall foliage. Carotenoids contribute to the yellow and orange shades, while anthocyanins produce reds and purples. As chlorophyll wanes, these vibrant colors emerge.<\/p>\n<\/div>\n

\u201cIt\u2019s a very cool process,\u201d McCallister adds. \u201cEach color absorbs different spectrums of light, altering energy uptake and preparing trees for leaf drop and dormancy. As leaves in deciduous trees transition, trees store energy in their roots and wood so they can brave the winter.”<\/p>\n

\"Close-up<\/a><\/p>\n<\/div>\n

Viewing Fall Foliage<\/strong><\/div>\n
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When it comes to enjoying fall foliage, McCallister emphasizes that Indiana offers many great viewing locations not far from Purdue\u2019s campus.<\/p>\n

Locally,\u00a0Martell Forest<\/a>, which is open to the public, is a great spot to check out the fall foliage and immerse yourself in the woods,\u201d says McCallister.<\/p>\n<\/div>\n

What’s Next?<\/strong><\/div>\n
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Leaf drop is likely to occur anytime from mid-October into December, although this process may take longer than usual due to the milder winters we\u2019ve been experiencing. Similar to color changing, the timing of leaf drop varies by tree species and their growth patterns, as well as the overall weather conditions.<\/p>\n

“For instance, ginkgo trees turn this brilliant yellow and have a cool reaction to leaf drop. Typically, all their leaves fall within a day or so, creating a carpet of yellow. In contrast, trees like maples and oaks, which have a mix of yellow, orange and red leaves, tend to hold onto their foliage a bit longer,” McCallister recalls.<\/p>\n

It’s also important to note that while coniferous trees, like pines, spruces and furs, retain their needles year-round, some conifers like bald-cypress trees drop theirs. This sometimes causes confusion for homeowners who mistake these deciduous conifers for dying trees.<\/p>\n

To provide the best care for your trees during these changing weather patterns, McCallister advises familiarizing yourself with different tree species. Resources like Google and dichotomous keys in forestry books can help with species identification and lead to tips for care. Regularly checking your trees\u2019 health is essential year-round. Specialists in your local county\u00a0Extension<\/a> offices and ISA Certified Arborists can be valuable resources for proper tree management.<\/p>\n<\/div>\n

To view the original article along with other news and stories posted on the Purdue Agriculture website see: Is fall foliage a sign of seasonal change or response to heat waves?<\/a><\/p>\n

Resources:
\n<\/strong>Find an Arborist<\/a>\u00a0video, Trees are Good-International Society of Arboriculture (ISA)
\nID That Tree<\/a>, Playlist, Purdue Extension \u2013 FNR YouTube Channel
\nInvasive Species Playlist<\/a>, Playlist, Purdue Extension \u2013 FNR YouTube Channel
\nA Woodland Management Moment<\/a>, Playlist, Purdue Extension \u2013 FNR YouTube Channel (Against Invasives, Garlic Mustard, Autumn Olive)
\nReport Invasive Species<\/a>, Purdue Invasive Species
\nInvasive Plants of the Eastern U.S.: An Introduction to the Problematic Non-Native Species<\/a>, The Education Store, Purdue Extension’s resource center
\nWhy Fall Color is Sometimes a Dud<\/a>, Purdue Landscape Report
\n\\U.S. Forest Service Fall Colors<\/a>, Forest Service, U.S. Department of Agriculture
\nID That Tree Fall Color: Sugar Maple<\/a>, Purdue Extension \u2013 Forestry and Natural Resources YouTube Channel, ID That Tree Playlist
\nWhat Are Invasive Species and Why Should I Care?<\/a>, Purdue Extension-FNR Got Nature? Blog
\nEmerald Ash Borer Information Network<\/a>, Purdue University and Partners
\nInvasive plants: impact on environment and people<\/a>, The Education Store, Purdue Extension\u2019s resource center
\nSubscribe<\/a>\u00a0Purdue Extension-Forestry and Natural Resources YouTube Channel<\/p>\n<\/div>\n

Devyn Raver<\/a>, Media Relations and Content Development Specialist
\nPurdue Forestry & Natural Resources<\/p>\n

Ben McCallister<\/a>, Urban Forestry Specialist
\nPurdue Forestry & Natural Resources<\/p>\n","protected":false},"excerpt":{"rendered":"

Purdue Agriculture News: As autumn settles in, we eagerly await the transformation of leaves into vibrant hues of red, orange and yellow. However, this year might tell a different story due to prolonged periods of hot weather. Ben McCallister, urban forestry specialist in Purdue University\u2019s\u00a0Department of Forestry and Natural Resources, sheds light on what to […]<\/p>\n","protected":false},"author":62,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[42,80,53,54,622],"tags":[1081,751,1070,1998,60,408,71,72],"class_list":["post-30043","post","type-post","status-publish","format-standard","hentry","category-forestry","category-trees","category-urbanforestry","category-wildlife","category-woodlands","tag-autumn","tag-fall-color","tag-fall-season","tag-foliage","tag-forestry","tag-trees","tag-urban-forestry","tag-wildlife","audience-for-enthusiasts","audience-for-homeowners","audience-for-landowners","audience-for-professionals"],"acf":[],"aioseo_notices":[],"publishpress_future_action":{"enabled":false,"date":"2026-04-21 07:18:57","action":"change-status","newStatus":"draft","terms":[],"taxonomy":"category","extraData":[]},"publishpress_future_workflow_manual_trigger":{"enabledWorkflows":[]},"_links":{"self":[{"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/posts\/30043","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/users\/62"}],"replies":[{"embeddable":true,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/comments?post=30043"}],"version-history":[{"count":8,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/posts\/30043\/revisions"}],"predecessor-version":[{"id":31789,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/posts\/30043\/revisions\/31789"}],"wp:attachment":[{"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/media?parent=30043"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/categories?post=30043"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/tags?post=30043"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}