Jeffers Foundation


Data from Freshwater Society Minnesota Weatherguide Environment Calendar and Almanac (Jim Gilbert for Phenology and Rod Nerdahl for Astronomy)


Phenology: Third Week of September

Honey bees, bumble bees, monarch butterflies, syrphid flies, and other pollinators are visiting the flowers of New England aster, stiff goldenrod, and Autumn Joy sedum. Garden chrysanthemums have very showy flowers. Highbush cranberry shrubs have clusters of bright red fruit. Rafts of American coots on many Minnesota lakes are a sign of autumn. Monarch butterflies continue migrating through; they stop to nectar on New England aster, butterfly-bush, Mexican sunflowers, and other flowers. Heading south at an average speed of 11 miles per hour, they will reach their winter home in the mountain forests west of Mexico City around the first of November. Virginia creeper vines have mostly bright red foliage, and many sumac shrubs are displaying beautiful tones of red. Wild grape leaves are turning a sunny-yellow. Fall colors are starting to peak from Lake of the Woods through the BWCAW.

View the September Phenology Information from the Freshwater Society Minnesota Weatherguide Environment Calendar and Almanac >>

Species of the Month

Common tree frog (Hyla versicolor)

Common tree frog (<em>Hyla versicolor</em>)
Jerry Hogeboom

The common tree frog, also called gray tree frog, is a one- to two-inch green animal with a white belly that can switch color to gray accompanied by dark spots as the temperature, humidity, or habitat changes. They are found in a variety of woodland habitats, usually near water, throughout Minnesota except in the southwest. Males are very vocal in June with their melodic trills. These small insect-eaters have toe pads and produce a sticky substance that allows them to climb smooth surfaces such as window panes without difficulty. On a September evening we often see them outside on our lighted window panes or screens catching insects.

Astronomy: September

When you are named after the Messenger god, you better be fast! Circling the Sun in just 88 days, Mercury moves quickly from east to west. Like Venus, Mercury reaches several benchmarks in its orbit, as seen from the Earth. Greatest Western Elongation is when it is furthest west of the Sun and Greatest Eastern Elongation is when it reaches its eastern limit. These points offer the best chance to see Mercury. In August, it will be 18 degrees west of the Sun, and in November, 23 degrees to the east. When Mercury is in line with the Sun and Earth, it is said to be in conjunction. Inferior Conjunction is when it passes between the Earth and the Sun, while Superior Conjunction is when it is behind the Sun.

Morning Stars

Mercury starts the month far from the Sun, having just passed Greatest Elongation. True to its name sake, it quickly reaches Superior Conjunction on September 20, passing behind the Sun as seen from the Earth.

Evening Stars

In the beginning of the month, Venus, Jupiter, Mars, and Saturn are all lined up across the south, 30 minutes after sunset. Venus is low in the west-southwest at 7.5 degrees altitude, Jupiter in the southwest at 18 degrees, Saturn in the south at 22 degrees, and Mars in the south-southeast at 12 degrees. Venus pulls away from the ecliptic, as it follows its orbit toward Inferior Conjunction next month. This makes the Moon's pass on September 12 not even that close. Jupiter gets a Lunar visit on September 13, Saturn on September 17, and Mars on September 19.

Sun Declination

View the September Astronomy Information from the Freshwater Society Minnesota Weatherguide Environment Calendar and Almanac >>


Last Baltimore oriole leaves to winter in Central America (from Minnetonka):
2016 September 14
2015 September 9
2014 September 17
2013 September 14
2012 September 8




2nd, Last Quarter Moon - 9:37 pm

3rd, Moon near Aldebaran rising in northeast - Before midnight

7th, Moon perigee (224,533 miles) - 8:19 pm

9th, New Moon Wild Rice (Ojibwe) - 1:01 pm

16th, First Quarter Moon - 6:15 pm

19th, Moon apogee (251,578 miles) - 7:53 pm

22nd, Autumnal equinox; fall begins N Hemisphere - 8:54 pm

24th, Full Moon - 9:52 pm

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