Halfway through October 2015, fall color had made a pronounced appearance across part of the Northern Hemisphere. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra and Aqua satellites captured these views of the changing fall foliage in the United States and Canada.

The top image, acquired with Aqua on October 11, 2015, shows leaf color around the Great Lakes; the bottom image, acquired with Terra on October 12, 2015, shows the U.S. Northeast and Canada’s eastern provinces. Sunlight and temperature are the primary factors responsible for the shift from green to shades of brown and orange.

Fall color generally peaks around mid-October as temperatures drop and sunlight fades. But the exact date of the peak is not the same everywhere. Northern latitudes see temperatures drop sooner and sunlight fade faster, so color will appear there as early as September. For example, striking fall color was already apparent in imagery from September 9 of eastern Siberia. Areas farther south can see peak color in mid-November. Elevation matters too, with fall color generally starting sooner at colder, higher altitudes.

Some years, however, turn up a more spectacular burst of color than others. It turns out that the weather before and during the transition plays a large role in color intensity. Brightest colors occur when dry, sunny days are followed by cool, dry nights.

The weather cooperated in some areas so far in 2015, providing vivid displays. For views closer to the ground, check out the video and photos in a blog post by The Washington Post’s Capital Weather Gang.

NASA images by Jeff Schmaltz, LANCE/EOSDIS Rapid Response. Caption by Kathryn Hansen.