Angel's Whisper Day

What Is Angel's Whisper Day?

Every February 17th is "Angel's Whisper Day" (天使の囁き記念日, Tenshi no Sasayaki Kinenbi) in Japan. On February 17, 1978, the weather observation post at Moshiri (母子里) in Horokanai Town (幌加内町), Hokkaido (an observation facility near Hokkaido University's research forest) recorded a temperature of -41.2°C. Because the facility was not a Japan Meteorological Agency station, the reading is unofficial, but it is lower than Japan's official record low of -41.0°C, observed in Asahikawa in 1902. In 1994, a local group, the "Tenshi no Sasayaki wo Kiku Kai," established the day as "Angel's Whisper Day" — a poetic name for the phenomenon of "diamond dust" (ダイヤモンドダスト, daiyamondo dasuto), the tiny ice crystals that float in the air at extremely low temperatures and catch the light like glittering dust.

Diamond Dust and Extreme Cold

"Diamond dust" (daiyamondo dasuto) occurs when the air temperature drops far below freezing and water vapor freezes directly into tiny ice crystals that float in the air and sparkle in sunlight — a phenomenon that is generally said to occur at around -10°C or below, and is seen more easily the colder it gets. The "angel's whisper" name for diamond dust evokes the magical, silent quality of these floating ice crystals that can be observed in the stillest, coldest winter mornings in Hokkaido's most extreme cold regions.

Horokanai: Japan's Cold Capital

Horokanai Town (幌加内町) in the mountains of central Hokkaido is one of Japan's coldest inhabited places — where winter temperatures can fall below -30°C and occasionally approaching the record lows that earned it its "angel's whisper" designation. The town's economy includes dairy farming (in summer), buckwheat cultivation, and increasingly, winter cold-weather tourism attracted by the diamond dust phenomenon and the extreme cold experience.

Cold Weather Tourism

Hokkaido's extreme cold winters have inspired a distinctive form of "cold weather tourism" — attracting visitors who want to experience phenomena including diamond dust, frost flowers (flowers of ice crystals that form on vegetation), and ice fog. Events celebrating cold weather, including Asahikawa Winter Festival (旭川冬まつり) and Horokanai's "Tenshi no Sasayaki wo Kiku Tsudoi" (天使の囁きを聴く集い), held since 1987, draw visitors seeking experiences only available in extreme cold.

Fun Facts

• Official vs. unofficial records: The -41.2°C Moshiri reading is unofficial because it was not taken at a Japan Meteorological Agency station. Japan's official record low remains -41.0°C, observed in Asahikawa on January 25, 1902.
• Breath clouds: At temperatures below -20°C, human breath condenses and freezes into visible clouds that linger in the still air — a phenomenon that makes even breathing a visible, dramatic experience in Hokkaido's coldest conditions.