By Julia · weather-au.com editorial team · Published · 4 min read
"Four seasons in one day" is the line Melburnians say about their own weather, and visitors are told to pack for it. It is a claim about how fast the weather turns, which means it can be tested. We took daily maximum and minimum temperatures for 2016 to 2025 (ERA5 reanalysis, Open-Meteo) for Melbourne and six other cities and ran four tests.
There is a limit to what we can say: the series has one reading per day, not one per hour. We cannot see the afternoon when a cold front arrives at 3 pm. What we can see is what happens from one day to the next, and the spread between a day's high and low.
Test 1: does the temperature jump from day to day?
We counted days on which the daily maximum differs by at least 10 °C from the day before.
Open-Meteo, ERA5 archive, 2016–2025 (reanalysis, not a weather station); calculation by the editors.
Verdict: confirmed. Melbourne has 16.0 such days a year, nearly double Adelaide (8.6) or Sydney (7.4), and well ahead of Hobart (6.5), Perth (4.7), Canberra (2.4) and Brisbane (0.6). For a swing of 15 °C or more the gap is even wider: Melbourne 3.2 days a year, every other city 0.5 or fewer, and Brisbane none in ten years.
Test 2: what does the biggest jump look like?
| Day | Maximum the day before (°C) | Maximum that day (°C) | Change (°C) |
|---|---|---|---|
| 5 Jan 2019 | 45.2 | 19.8 | −25.4 |
| 22 Nov 2019 | 41.8 | 19.6 | −22.2 |
| 10 Dec 2019 | 38.8 | 16.7 | −22.1 |
| 31 Dec 2019 | 42.4 | 21.2 | −21.2 |
| 7 Jan 2018 | 42.2 | 22.0 | −20.2 |
| 20 Dec 2019 | 23.8 | 43.7 | 19.9 |
| 28 Jan 2025 | 41.0 | 21.4 | −19.6 |
| 26 Jan 2021 | 40.0 | 20.8 | −19.2 |
Open-Meteo, ERA5 archive, 2016–2025 (reanalysis, not a weather station); calculation by the editors.
Seven of the eight biggest swings are drops, from a day above 38 °C to one under 23 °C: from 45.2 °C to 19.8 °C between 4 and 5 January 2019 is a fall of 25.4 °C in a day. The exception is a rise, from 23.8 °C on 19 December 2019 to 43.7 °C the day after. The pattern explains the reputation: a very hot day in Melbourne often ends abruptly.
All eight fall between November and January, which is worth a closer look at the calendar.
Test 3: when do the jumps happen?
Open-Meteo, ERA5 archive, 2016–2025 (reanalysis, not a weather station); calculation by the editors.
Verdict: it is a spring and summer phenomenon. Of the 16 jumps a year, December has 3.6, January 3.2, February 2.6, March 2.5 and November 2.4. From May to August the count is zero: not a single day in ten winters on which the maximum moved 10 °C from the day before. So "four seasons in one day" in July does not hold in the data. In July the maximum is a steady 12.8 °C (normal) and the nights are 6.4 °C.
Test 4: is the gap inside a day unusually large?
Here the reputation falls apart. A day when the maximum and minimum are 15 °C or more apart happens 42 times a year in Melbourne, which is more than Adelaide (23), Perth (22), Brisbane (18), Sydney (16) or Hobart (15). But Canberra reaches 62 days a year, and its average daily range is 11.3 °C against Melbourne's 9.4 °C. Dry inland air cools quickly after dark; sea air does not.
Verdict: false as a claim about one day. Melbourne's day-to-night gap is ordinary. What is unusual is the gap between one day and the next.
| City | Days a year, maximum 10 °C+ different from the day before | Days a year, maximum 15 °C+ different from the day before | Days a year, gap between maximum and minimum of 15 °C+ | Normal rain days a year (≥ 1 mm) | Normal rain a year (mm) |
|---|---|---|---|---|---|
| Melbourne | 16.0 | 3.2 | 42 | 105 | 616 |
| Adelaide | 8.6 | 0.4 | 23 | 78 | 489 |
| Sydney | 7.4 | 0.5 | 16 | 112 | 879 |
| Hobart | 6.5 | 0.2 | 15 | 120 | 631 |
| Perth | 4.7 | 0.4 | 22 | 73 | 550 |
| Canberra | 2.4 | 0.1 | 62 | 79 | 568 |
| Brisbane | 0.6 | 0.0 | 18 | 100 | 855 |
Site normals 1991–2020 (ERA5 reanalysis) and Open-Meteo ERA5 archive 2016–2025; calculation by the editors.
And the rain?
Visitors are also told to expect drizzle all year. The site's 1991–2020 normals give Melbourne about 105 rain days (at least 1 mm) a year and 616 mm of rain. Sydney has 112 rain days and 879 mm; Hobart 120 days and 631 mm; Brisbane 100 days and 855 mm. So Melbourne has nearly as many wet days as Sydney (105 against 112) but about 30% less rain. If you pack an umbrella, it is for light rain more often than for downpours.
The weeks that really did have everything
A last count, closer to the saying. We looked for seven-day windows in which the hottest day reached 30 °C or more and the coldest day's maximum was 15 °C or less. Counted by starting day over the ten years, Melbourne has 34 such windows, Hobart 23, Adelaide 13, Canberra 4, Sydney 3, and Perth and Brisbane none. Hobart comes second here although it is fourth in test 1, a reminder that the two tests measure different things.
How to pack, according to the data
- Layers, not a coat. From November to March a hot day can end with a 10 °C drop; carry something light that you can add in the evening.
- Do not plan the day by the morning. The typical Melbourne jump happens between days, so the forecast for tomorrow matters as much as today's.
- In winter, relax. May to August brought no 10 °C overnight swing in ten years; winter is cold and steady (the Melbourne page gives the next 14 days).
For a visit month by month, see when to visit Australia.
Period of the data cited: 2016–2025.