Fog dense enough to prompt a weather warning will accompany the first day of the live stream of sunrise from the chamber at Newgrange in Co Meath.
Met Éireann has issued a yellow weather warning for the whole of the State until 11am on Monday morning. Otherwise Christmas week promises to be mild with no prospect of a white one.
The winter solstice is to be streamed online for the second year in a row because of Covid-19 concerns, the Office of Public Works (OPW) has said.
Minister of State for the OPW Patrick O’Donovan said he understood there was “disappointment” about the closure of the passage tomb’s chamber because of the pandemic, especially for the winter solstice on Tuesday.
“But we have to be mindful of the Government guidelines in relation to Covid-19 and the health and safety of our visitors at all times,” he said.
While the chamber cannot be accessed, the OPW will broadcast winter solstice sunrises live online from this morning until December 22nd.
“Watching the light creep into the 5,000-year-old passage tomb in real time is a moving event that has the power to fill us both with wonder at the ancient architects’ ingenuity and with hope for the future,” Mr O’Donovan said.
The solar alignment of the passage tomb at Newgrange to face the rising sun on the winter solstice was originally rediscovered by Prof Michael J O’Kelly in 1967. Other researchers have since then validated O’Kelly’s interpretation.
Analysis of high-resolution imagery taken during last year’s research programme has added to the body of evidence that the solar illumination of the tomb was intentional.
“The solstice has long been celebrated as a time of rebirth and renewal as we look forward to the prospect of brighter days ahead,” Minister of State for Heritage Malcolm Noonan said.
“As we continue our Newgrange Solstice Research Project I am very excited to learn more about how the dawn sun on the shortest days of the year interacts with this remarkable monument and how it may have engaged and enthralled our ancestors over five thousand years ago.”