Cold front ploughing across TAS on Thursday.

November top-up for the Snowy Mountains. link.dataspace.copernicus.eu/lqip

An incursion of dry, polar air brought widespread frost and a swag of November record low temperatures across south east Australia on Wednesday morning. Records for stations with 15+ years of history are highlighted.

This cold front, and tonight's late-season frost under the dry air behind it, are the latest effects of ongoing negative AAO/SAM on south east Australia.

Another burst of strong westerlies (then shallow coastal southerlies) across eastern NSW on Tuesday, before dry and rapidly stabilising air brings late-season frost to the ranges and slopes.

Dry, stable air in the wake of a cold front will produce late-season frost across prone parts of south east Australia on Wednesday morning.

Typhoon Fung-wong / Uwan near the Philippine coastline.

Tropical Storm Fung-Wong building over the Philippine Sea. The system is expected to intensify and cross northern parts of the Philippines early next week.

Low pressure system over Central West WA on Wednesday.

Cross section of the 2025 southern polar vortex in the middle stratosphere. Disturbances propagating up from the troposphere since September have caused this year's vortex to dissipate more quickly than usual.

Multi-centred low pressure system bringing fresh westerly winds and wintry showers across south east Australia.

Thunderstorms ahead of and behind the cold front crossing south east Australia, and along the trough extending to its north.

Polar and tropical air masses interacting over south east Australia.

Severe thunderstorms affecting parts of eastern NSW on Friday evening.

A shortwave rippling across eastern Australia will combine with a surface trough to produce showers and thunderstorms on Friday and Saturday.

Eastern Australia has gone from dry, stable westerlies in mid-October to something a little more showery for the start of November. Here's how the broad-scale pattern has evolved. Note that negative AAO/SAM (reds over Antarctica) hasn't quite dissipated yet.

Outflow from morning thunderstorms over the Top End serves as a trigger for afternoon thunderstorms over the Kimberley.

Cloud at two different levels producing showers over Sydney this morning. The bands from the north east are from lower cloud and those from the north are from higher cloud.

Hurricane Melissa tracks across Jamaica on Tuesday.

Category 5 Hurricane Melissa nearing the Jamaican coastline on Tuesday morning, exhibiting extreme structure and intensity.

Hurricane Melissa approaching Jamaica. The category 5 system brings catastrophic winds, flooding and storm surge.

The US NHC estimates category 5 Hurricane Melissa's central pressure to be 901 hPa at 06:00 UTC. The system is expected to bring catastrophic winds, flooding and storm surge to Jamaica on Tuesday.

Category 5 Hurricane Melissa approaching Jamaica on Monday evening.

A developing upper-level trough will produce showers and thunderstorms over parts of eastern Australia during the next few days.

Cold southerly change crossing eastern NSW on Monday.

Potential for a little rain this week over parts of eastern Australia that could use it.

A relatively warm polar air mass and consequent negative SAM have dominated southern weather patterns during October: wavier jet streams, a series of storms south of Australia and New Zealand, a persistent ridge over Australia, and sustained westerlies between.

The low that slipped through Bass Strait on Wednesday approaching southern parts of New Zealand, en route to becoming a 940 hPa storm over the Southern Ocean.

The 987 hPa low responsible for the wind across south east Australia. The system is moving quickly eastward, so Thursday will be much calmer for most.

October heat records dropping like flies across central and eastern Australia. The map shows new records for locations with at least 20 years of history.

Temperatures climbed quickly to record October highs across a number of Sydney suburbs once north westerly winds mixed down to the surface. Of the locations to top records so far, Bankstown has the longest period of record at 57 years.

Low pressure system approaching Bass Strait producing damaging to destructive winds and extreme fire danger over parts of south east Australia on Wednesday.

Damaging to locally destructive winds will affect south east Australia on Wednesday, brought about by a tight low over Bass Strait and a cold front extending to its north.

Projection from BOM's high-resolution ACCESS-C model showing the strong cold front expected to cross south east Australia on Wednesday, and the heat preceding it.

Recent negative AAO/SAM has resulted in very warm days across most of Australia, with cooler conditions confined to the south/west facing fringes. Contrasting air masses always mean wind, and that will come to a head over south east states on Wednesday.

Negative SAM. Not your cynical mate's nickname, but the reason there are mountain waves over eastern NSW in late October.

Negative AAO/SAM related to recent warmth over Antarctica 🟥, storms over the mid-latitudes 🟦, and the ridge over Australia 🟥 that's giving October heat records a nudge.

Two bursts of heat are expected to cross southern Australia over coming days, with maximum temperatures up to 16°C above the October average.

Heat building over Australia's northern interior will pay southern parts a couple of visits during the next week.

Clear Antarctic skies resulting from the (relatively) warm, stable air currently over the polar region. Ice appears blue in this false-colour imagery.

Short-lived southerly change clipping south eastern NSW.

Typhoon Halong south east of Tokyo on Thursday.

Series of sliding cold fronts drawing a northwest cloud band across southern Australia this week.

Recent south polar warmth (negative AAO → SAM; gradually easing) has pushed westerlies further north, and produced a wavier jet stream pattern with persistent mid-latitude cold and warm anomalies. Which longitudes are cold/warm is governed by planetary waves.

Cold front crossing VIC, NSW and the ACT on Thursday.

Australian region sea surface temperatures during 2025 to date.

Twin Hurricanes Humberto 👉 and Imelda 👈 over the Atlantic Ocean.

Lift over the Mount Lofty Ranges creating a band of cirrus that extends to the Tasman Sea.

The infamous Sydney hailstorm of 14 April 1999. Data from openradar.io.

The southern polar vortex (stratospheric) heading for an early demise in 2025.