Above: A December morning shadow on a Maui beach.
Hawaii is the only state in the United States in which the sun can be completely overhead on certain days. For a moment on those days, no shadows are cast from people, telephone poles or other objects standing perpendicular to the ground. This natural phenomenon happens twice each year within a few weeks of the summer solstice on different days and times in the Hawaiian islands.
According to the LoveBigIsland website, the Big Island’s second Lahaina Noon of this year will happen on the following days and times:
Oahu residents and visitors in the Honolulu area can observe Lahina Noon, also known as solar noon, near Honolulu Hale at Sky Gate, a sculpture by the Japanese American artist Isamu Noguchi (1904-1988).
From the Bishop Museum website:
In the tropics the sun passes overhead twice during the year. On these two days, at local noon, the sun will be exactly overhead and an upright object such as a flag pole will have no shadow. This phenomenon only occurs in the tropics; the sun is never overhead in any other part of the planet. The northern reaches of the Hawaiian Islands, such as Midway Island, are north of the tropics and do not experience the overhead sun.
The ‘overhead sun’ date varies depending on how far north or south you are in the tropics. Thus, for Līhu‘e on Kaua‘i, this occurs on July 12, at 12:42 p.m. Further south, on the Island of Hawai‘i, the overhead sun date occurs on July 27 (12:26 p.m. for Hilo, 12:30 p.m. for Kailua Kona).
Here in the islands a term we often use for zenith noon is “Lāhaina Noon.” This is a modern term, selected by Bishop Museum in a 1990 contest held to select a name for the zenith noon phenomenon. The term “Lā haina” means ‘cruel sun’ in Hawaiian, and while the sun in the islands is almost never cruel, it can be pretty intense as it shines directly down from the zenith.
Another phrase that one hears in Hawai‘i for the zenith sun is “kau ka lā i ka lolo,” which translates as “the sun rests on the brains.” This expression is discussed in the book 1972 book Nānā I Ke Kumu (Pukui et. al.) as being a “phrase designating high noon; the time when ‘the sun is directly overhead and the shadow retreats into the body’… In view of all this, what we now call ‘high noon’ was thought to be a time of great mana (spiritual power).”  While this passage has be cited by some writers to suggest that “kau ka lā i ka lolo” is thus the traditional Hawaiian term for the ‘zenith sun,’ the phrase seems to refer to “high noon” on any day, and not specifically to those two days a year when the sun is exactly overhead. Thus, in Honolulu on May 23 at 12:28 p.m., one can certainly use the term “kau ka lā i ka lolo” to describe the sun’s position as it sits exactly overhead. However, that same expression “kau ka lā i ka lolo “can be used to describe the sun’s position on any other day at local noon (at least for the non-winter months, when the sun is quite high in the sky at local noon), and does not specifically refer to the phenomenon of ‘zenith noon’ itself.
Be sure to check the weather on the day you’ll want to experience this special event on the Big Island. This will be a good day to be sure you’re in the sun!
Source: Giambelluca, T.W., X. Shuai, M.L. Barnes, R.J. Alliss, R.J. Longman, T. Miura, Q. Chen, A.G. Frazier, R.G. Mudd, L. Cuo, and A.D. Businger. 2014. Evapotranspiration of Hawai‘i. Final report submitted to the U.S. Army Corps of Engineers—Honolulu District, and the Commission on Water Resource Management, State of Hawai‘i. Accessed July 2018.