We're at the peak of the long dark nights as we approach the winter solstice, which this year is at precisely 2.57am New Zealand Time tomorrow, Thursday June 22, says WeatherWatch head forecaster Philip Duncan.

After this moment, the earth begins its gradual roll back towards summer for the Southern Hemisphere.

"But just like the longest day in summer - shortly before Christmas Day, there is a delay with the temperatures."

The hottest weather comes weeks later in late January and February.

Philip says the shortest day behaves the same way.

"We wait until July and August for our coldest weather to kick in."

He says psychologically, many people prefer to focus on the positives - such as the days becoming longer again despite the cold.

"Here at WeatherWatch.co.nz we've noticed this is unique to the Winter Solstice and not the Summer Solstice, as in summer people don't instantly start wanting, or noticing, the days slowly getting shorter as we go through January and February."

The solstice is a precise moment in time. Solstices occur because Earth's axis of rotation is tilted about 23.4 degrees relative to Earth's orbit around the sun.

"Tomorrow the sun will be at it's northern most point - bringing the day with least amount of sunlight to the Southern Hemisphere and the 'longest day of the year' to the Northern Hemisphere.

"So next week, yes, the days start to very very slowly get longer again...but only by a few seconds or minutes to begin with."

Philip says most farmers and early rises tend to properly notice the longer days and extra sunlight again by the last week of July and first week of August - around one month from now.

"Many people in the north of NZ say early August can feel more like spring but it was only 2011 that snow flurries fell in Auckland city and the hills of Northland.

"So in New Zealand you can never be sure of what lies ahead over the next three months."

Philip says it's worth noting many calendars publish the winter solstice date/time in UTC, which this year would say 2.57pm Wednesday (England time) - but in NZ that is 2.57am Thursday.

On the bright side:
• Days gradually start to get longer / brighter again from July (noticeable four weeks from now)
• The Solar Winter (the three months of the year with least available sunlight) will be half way done by this Thursday...meaning in six weeks time the Solar Winter is over.
• You can give yourself positive news by telling yourself we're on the slide to Summer (even if only in your head at this early stage!)
On the dark side:
• Usually gets wetter and colder for the next two months ahead
• Limited sunlight before and after school/work
• Increased risk of wind chill affecting livestock
• Higher risks of depression and anxiety due to SAD

Philip Duncan, WeatherWatch.co.nz