Winter in Tasmania conjures up images of a snow-capped kunanyi/Mount Wellington and frosty starts to the day.
But the reality is that winter brings all kinds of possible weather around the state, with the typical winter weather pattern usually resulting from a belt of westerly winds known as the "roaring forties".
Residing approximately 40 degrees south of the equator, this belt of westerly winds usually moves up over Tasmania during winter and brings cold fronts across the state.
In summer, the roaring forties usually lie further south over the Southern Ocean, which is one of the reasons why cold fronts are less common in Tasmania at that time of the year.
Winter cold fronts
A cold front is the leading edge of a mass of cold, dense air that usually signifies a marked change in weather.
The many cold fronts that cross Tasmania during winter usually consist of lines of rainfall, wind and a sudden temperature drop.
Behind the cold front is where the cold air comes in. It can be accompanied by patchy showers with sometimes gusty south-westerly winds, sleet, hail or snow, depending on the temperature of the atmosphere behind the change.
Thunderstorms are also possible in the cold airmass behind some cold fronts, though they are not usually impressive.
As bands of rain and areas of showers cross the state from the west, they "rain out" a lot of the moisture they contain, meaning that the amount of rain or snow is often significantly less in eastern and northern parts of Tasmania during winter when compared with the west.
With winter sun comes frost and fog
In between these cold fronts there is often pleasant, sunny weather with high pressure systems quickly extending ridges of high pressure over the state.
These days feel warm with relatively light winds, but they usually involve very cold mornings and lots of frost or fog.
Frost is common about higher ground on days with light winds and clear skies, but often on still days the cold air from the mountaintops can "drain" down into valleys overnight.
This is known as katabatic winds — cold, dense air that falls from the mountain tops down into valleys below under the force of gravity.
This leads to many days starting below 0 degrees Celsius for inland parts and in sheltered valleys, but the afternoons usually feel quite mild by comparison.
Fog is also a regular in a Tassie winter, particularly valley fog.
It is most common in the Tamar Valley, Fingal Valley, Midlands, Upper Derwent Valley, and Huon Valley.
Sometimes, the fog can last all day in the Upper Derwent or even in Launceston — stopping the sun getting through and warming them up during the daytime.
Winter temperatures — how cold can it get?
Cold mornings are part of living in Tasmania, especially in winter.
The coldest temperature recorded in Tasmania was -14.2C at Liawenee up on the Central Plateau, however this weather station has only been in operation since 2000.
It is likely colder temperatures have been experienced around the state as temperature is not recorded on most mountain peaks.
The coldest inhabited places are those at elevation like Liawenee, or in sheltered valleys below.
Both Hobart and Launceston usually experience their coldest days and nights in July (or close to it).
The coldest minimum reported temperature at Hobart's Ellerslie Road weather station was -2.8C on July 11, 1991 and June 25, 1972.
The coldest temperature recorded at Launceston's Ti Tree Bend site was -5.2C on July 23, 1991.
Older records from Launceston City show a record of a -6.1C on 10 July, 1903.
The 'feels like' temperature
Also called the "apparent temperature", the "feels like" temperature is calculated to give an idea of how an average person would feel outside in the elements, taking into account wind and humidity levels.
In cooler months like winter, relative humidity is less of a factor in how comfortable a given temperature will feel.
Instead, wind chill becomes more dominant — windy days will feel colder than calm days.
While wind chill is a factor all year around, in winter the temperature is colder to begin with, so a 'chilling' effect on a cold temperature is why wind blocking jackets are a must-have in Tasmania.
What the "feels like" temperature does not take into account is how the sun might feel on your skin.
Some studies have found that sun shining on your skin can make the temperature feel up to around 8C warmer than it actually is.
Using that in a Tasmanian example of a 12C July day with full sun and light winds, you might be tricked into thinking it was 20C even if there was snow on the mountain.
On the other hand, imagine it is showery and cloudy, with brisk and icy southerly winds – suddenly that 12C might feel a lot closer to 0C.
The outlook for winter in Tasmania
The latest climate long-range forecasts, published on May 25, 2023, are indicating a strong likelihood of below normal rainfall for the northern half of Tasmania this winter, while the southern half should see normal rainfall amounts.
Both maximum and minimum temperatures are looking to be above average as well, with most of the state three to four times more likely to experience unusually warm temperatures at times (on average).
Even though the outlook is showing signals for warmer and drier conditions this winter, it is important to remember they come from a longer-term weather model — which shows us more of an average of expectations.
It is still very possible to have significant rain events and cold outbreaks throughout this winter.
Luke Johnston is a senior meteorologist at the Bureau of Meteorology Tasmania
For more information on likely rainfall and temperature for the months ahead, you can view the latest long-range forecasts on the BOM website.
