The colors of the moon
There have been articles in the past that have focused on the moon. Many of our long-range forecasts are often based on the lunar cycles. Potent storm systems usually need the support of the upper-level winds as they move across the continents to produce significant precipitation. Longtime observations and data analysis show a correlation with the lunar cycles and behavior of the upper-level jet stream patterns.
Last week was the first full moon of April in the Northern Hemisphere and was called the “Pink Full Moon.” Despite the name, the moon doesn’t usually appear pink in color. Instead, Earth’s satellite is typically bright and white when it lights up the night sky, especially when it’s high overhead.
The moon does not generate its own light as it reflects sunlight. When the moon is overhead, its light travels a shorter distance through the atmosphere and there are fewer air particles and pollutants. This allows most of the colors in sunlight to reach our eyes without much scattering, resulting in the moon’s white or slightly silvery hue.
However, there are times when the full moon may appear to have a rosy or pinkish tint. This happens mostly during a moonrise or moonset, when the moon is low on the horizon. During these times, the light from the moon must pass through more of the Earth’s atmosphere, which scatters shorter blue wavelengths and allows longer red and orange wavelengths to dominate. Under the right conditions, especially if there are dust particles, pollution or haze in the air, the moon may appear to have a warm and slightly pink hue to the viewer.
The “Pink Moon” originates from Native American and early colonial traditions, which often tied full moons to seasonal events. It refers to the blooming of a wildflower known as Phlox subulata, or moss pink. These tiny flowers, which blanket the ground in shades of pink and purple in early spring, were considered to be one of the first signs of life returning to the landscape after a long winter.
The Pink Moon is also part of a rich tradition of lunar naming that includes the Harvest Moon, the Wolf Moon and the Strawberry Moon. They reflect what people observed in their environment during specific times of year.
Some of the most spectacular visions of the full moon are when it’s near the horizon. At this time, we will often see the moon take on a golden or yellowish tone. This happens because the moonlight must travel through a thicker slice of the Earth's atmosphere to reach the observer. Along the way, shorter wavelengths of light, like blue and violet, are scattered out by particles in the air. This leaves behind the longer wavelengths that include reds, oranges and yellows. When it reaches our eyes, it can provide stunning sunrises and sunsets.
On rare occasions, we may see a “purple” full moon. This phenomenon can occur when conditions and the timing are perfect, as the atmosphere is filled with fine particles that scatter both red and blue light equally, leaving a blended purple hue.
When we hear of a “blue moon,” this refers to a second full moon in a calendar month. The next time we’ll have two full moons in a month will be in May 2026. Although a blue moon does not relate to color, there are also rare occasions when it may appear bluish. This can happen during specific atmospheric conditions when there is fine smoke, dust particles from forest fires or volcanic eruptions in the air.
A “red moon” that’s high in the sky is often associated with a total lunar eclipse called a “blood moon.” During an eclipse, the Earth passes between the sun and the moon, casting its shadow on the moon and causing it to appear dimmed or even reddish. This phenomenon blocks direct sunlight from reaching the moon, and the only light that filters through the Earth’s atmosphere is red, which bends around the planet, often creating a reddish glow. The next total lunar eclipse visible from Coeur d'Alene will occur March 3, 2026.
In terms of our local weather, as of the weekend, approximately 0.40 inches of moisture has fallen in Coeur d’Alene this month, compared to the April normal of 1.77 inches. There is a chance of some measurable rainfall this week, but it looks like we’re going to fall short of the month’s normal precipitation.
Rainfall is expected to increase in May, and we should be close to the 2.37-inch normal in Coeur d’Alene. The long-range forecast models are indicating that we’ll have that wetter weather pattern during the first week of next month. The cooler-than-normal sea-surface temperature event, La Niña, has dissipated. As ocean waters are expected to warm slightly, the upcoming summer season still looks drier than normal, but we don’t believe that our region will be as dry as 2024, when only 1.59 inches were reported the entire summer. Stay tuned.
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Contact Randy Mann at randy@longrangeweather.com.