Ever since the calendar ticked over to March, we've been dreaming of digging out our favourite Autumnal fashion staples. But as anyone in Sydney right now will tell you, the weather isn't exactly conducive to cute jackets and trench coats. The air feels thick, the nights are sticky, and even a brief walk outside leaves a sheen of moisture on the skin (and not in a chic rhode-glazing-milk kind of way).

If it's been feeling abnormally humid to you, you're not imagining it — scientists have confirmed that Sydneysiders have been enduring an unusually humid stretch that rivals conditions normally reserved for peak summer in Queensland. Here's why.

Temperatures really have been higher

This year, March is running hotter than usual. Observations recorded by ABC Australia show a mean daily high of 27.9°C, with overnight lows lingering around 20.8°C. That’s roughly 3°C above the long-term average for the city. When humidity is factored in, the apparent temperature (i.e., how hot it feels) has peaked at 32°C in sheltered spots.

But the humidity makes it feel even hotter

So what makes this spell feel so oppressive? It’s not just the warmth; it’s the moisture in the air. Meteorologists often measure this through what's called the dew point, which tracks how much water vapour the air contains. Sydney’s average dew point this March is around 20°C, which is far above the long-term March average and even higher than Brisbane at the same time of year.

So why is it so humid?

Two main factors are driving the mugginess. First, persistent northerly winds have pushed tropical air south, bringing both heat and moisture. Second, the Tasman Sea is unusually warm — up to 3°C above normal. Warmer sea surfaces increase evaporation, loading the atmosphere with water vapour, which onshore winds then push over to us on land.

A southerly change is set to arrive from today, promising temporary relief with dew points dropping into a comfortable 10–15°C range for a few days. But it won’t last, as Northeasterly winds are predicted to return next week, restoring the high moisture levels.

This unseasonably humid March is also part of a longer-term trend. Over the past century, Sydney’s mean annual temperature has reportedly risen by roughly 1.5°C, pushing it closer to Brisbane’s historical climate. Under high emissions scenarios, projections suggest that Sydney could see a climate similar to the Northern Rivers by 2050 and the Wide Bay region of southeast Queensland by 2090.