Blue Moon Returns May 31, 2026 as Month’s 2nd Full Moon

9 articles · Updated · Forbes · May 27

May 31 will bring a rare monthly Blue Moon — the second full moon in a single calendar month after the Flower Moon on May 1.
The event stems from the mismatch between the moon’s 29.5-day cycle and longer calendar months, creating enough time for two full moons in May.
Saturday, May 30 at dusk offers the best viewing, when the moon rises in the east and appears orange near the horizon rather than blue.
That warm color comes from Rayleigh scattering in Earth’s atmosphere, which filters out shorter blue wavelengths and lets red-orange light dominate.
The next monthly Blue Moon is due on Dec. 31, 2028, while the next seasonal Blue Moon arrives earlier on May 20, 2027.

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