You've got to love this time of year.

Autumn is a time when contrasting airmasses cause wildly differing conditions across Australia, with tropical cyclones, Antarctic cold fronts, tropical lows, dry heat and pretty much everything in between.

And the satellite image on the first day of Autumn 2021 shows exactly that.

In the top left corner, Severe TC Marian can be seen southwest of Cocos Island, an Australian territory about halfway on an imaginary line between Perth and Sri Lanka. The Category 3 storm is expected to track southeast on Tuesday before weakening and should not adversely affect the WA coastline.

Image: Monday morning's Himawari-8 satellite image is the meteorological equivalent of a box of chocolates.

At the other end of the image, classic Southern Ocean speckled cloud can be seen approaching Tasmania. The speckle indicates cold, moist air, and snow is predicted for the higher peaks of Tasmania - including Kunanyi/Mt Wellington on the outskirts of Hobart - later this afternoon or evening.

Southern Victoria will also be flicked by the cool air, with maximums of just 17°C and 18°C on Tuesday and Wednesday, and tops unlikely to exceed 21°C in Melbourne for the whole of the working week.

In the top right corner of the satellite image, cloud associated with a low pressure system can be seen near the Queensland coast. Heavy rain is forecast for parts of north Queensland in the next few days.

And between all those cloud masses, the majority of New South Wales looks mostly dry. Northwesterly winds will push warm dry, inland air across the state, with temps nudging 40°C in the northwest, and highs in the mid-30s across much of NSW, including western Sydney.

The Sydney CBD should see a top of 33°C before a southerly change late this evening. The rest of the week should then be mild, with only a slight chance of a few light showers.