Photo via The Guardian

Sydney and parts of NSW swelter through temperatures in the 30s before plummeting 10C within hours

Read the original at The Guardian ↗
Cite

Caldwell, I. (2026, September 21). Sydney and parts of NSW swelter through temperatures in the 30s before plummeting 10C within hours. The Guardian. https://www.theguardian.com/australia-news/2026/sep/21/sydney-nsw-weather-temperatures-hot-to-cool-within-hours

Dated when The Aporia collected the article, usually within hours of publication. Check the original for its exact date and byline.

The Guardian · collected 2026-09-21 · by Ima Caldwell

Quick Summary

Sydney and parts of New South Wales experienced unusually high temperatures over the weekend and early this week, with some areas reaching up to 35°C, more than 10°C above average for September. The heat wave was followed by a sudden drop in temperature by about 10°C within hours as a cool change moved through. Authorities issued fire danger warnings due to dry and windy conditions, but these risks are expected to decrease with the cooler weather moving in. The Bureau of Meteorology attributes this unusual weather pattern to an approaching El Niño event, which is forecasted to be one of the strongest since record-keeping began in 1950.
Written by AI on 2026-09-21, from this article's own text only (the story summary below draws on all the coverage).

AI analysis

Story summary

Sydney and parts of New South Wales experienced unusually high temperatures in early September, with some areas reaching up to 35.4°C on Monday. This heatwave was part of a "spring rollercoaster" phenomenon, where temperatures spike above average for the season before rapidly dropping. In Sydney's outer west, Richmond hit 35.4°C, while Penrith reached 35°C. The city itself saw its temperature peak at 32.7°C at Sydney Observatory Hill early on Monday afternoon.

By late afternoon, temperatures dropped by about 10°C due to a cool southerly change sweeping through the region. Weatherzone reported this sudden shift as part of a broader weather pattern affecting southeast Australia over the weekend. The Bureau of Meteorology spokesperson forecasted cooler conditions and light showers for Tuesday and Wednesday in Sydney, influenced by the changing wind patterns.

Written for “Australian Weather Extremes” on 2026-11-01, grounded in this article and the 0 other(s) covering the same event.

Story

📰 Australian Weather Extremes
Environment · 1 article(s) covering the same event.

Compared with similar articles

This article reads unscored and hedges 11% of its claims. Each row says how that neighbour differs.
ABC News (AU)
Hedges 1 of 24 claims Outlet record 68/100
“While both articles describe extreme temperature changes in Australia around the same time period, they focus on different phases of the weather event and cover different geographic areas.”
How this article was measured signals, leaning charts, publisher record, byline, topics and claims

Signals How these are calculated →

Claims extracted
18
sentences that state something as happening or true
Uncertain
11%
2 of 18 hedged ("reportedly", "may", "according to")
Leaning
not political
takes no side on a contested political question
Publisher signals
66/100
The Guardian's corrections and hedging, across everything collected from it. Not a measure of accuracy.
Outlets on this story
1
Environment
Same framing elsewhere
1
articles that frame the event the way this one does
Analyzed 2026-09-21 · how these are computed

How this is being covered How these are calculated →

Article leaning vs. publisher reliability
Source leaning vs. consistency

Publisher

The Guardian · 2795 article(s) · 6 correction(s) detected
Running correction rate · 6 correction(s)

Who wrote this

Ima Caldwell
5 article(s) here · 1 carrying a prediction
🔮 “Lapwings will often become accustomed to the local patterns of people using a site and in many situations people modify their behaviour to avoid the core nesting area,” Holdsworth said.
🔮 It is horrifying to think how much worse this could have been,” Grech said.
🔮 We will always stand on the side of renters.”
🔮 Temperatures in Sydney’s outer west reached 35.4C in Richmond and 35C in Penrith on Monday, just before forecasted cold snap via a south-southeasterly change.
🔮 A new institute dedicated to improving emergency medical care for severely injured children will be established in New South Wales following recent high-profile trauma events in the state.
Also by Ima Caldwell
Nothing else under this byline is closely related to this article, so these are simply their most recent.

Topics

Australia El Niño New South Wales Sydney Weatherzone

Subjects

Sydney GPE · 6× Australia GPE · 3× New South Wales GPE · 2× Weatherzone ORG · 2× Bureau of Meteorology ORG · 1× Cessnock PERSON · 1× Guardian Australia ORG · 1× Muswellbrook GPE · 1× Penrith GPE · 1× Sydneysiders NORP · 1×

Narrative

For now, Sydneysiders can now expect a much cooler, wetter outlook for the coming days under the influence of a cool southerly airstream. “We expect the temperatures to be on the cooler side for tomorrow into Wednesday… together with cloud overcast and light showers,” the bureau spokesperson said.
framing: assertive · carried by 1 article(s) · first seen 2026-09-21
🔮 Temperatures in Sydney’s outer west reached 35.4C in Richmond and 35C in Penrith on Monday, just before forecasted cold snap via a south-southeasterly change.

Claims (18 extracted, 2 hedged)

Sydney and parts of New South Wales have sweltered through an “unseasonably warm” weekend, with temperatures climbing more than 10C above the September average, before a cool change swept much of the coast on Monday. asserted
change → swelter → Monday
The early burst of heat, part of a classic “spring rollercoaster”, brought summery hot weather conditions to the state. asserted
burst → bring → state
Weatherzone reported that a wave of heat swept across south-eastern Australia over the weekend, before the peak of the heat hit Sydney on Monday. asserted
peak → report → Monday
Temperatures in Sydney’s outer west reached 35.4C in Richmond and 35C in Penrith on Monday, just before forecasted cold snap via a south-southeasterly change. asserted
Temperatures → reach → change
The city also sweltered. asserted
city → swelter → ?
Sydney Observatory Hill reached a high of 32.7C at 10.40am, before temperatures plummeted significantly by about 10C within a couple of hours, a Bureau of Meteorology spokesperson told Guardian Australia on Monday afternoon. asserted
spokesperson → reach → afternoon
On the weekend, easterly sea breezes brought some relief to coastal areas, keeping eastern Sydney a few degrees cooler than the west. asserted
breezes → bring → west
On Sunday, western suburbs recorded maximums of about 34C, while the city recorded 28.9C. The spokesperson said temperatures were “unseasonably warm in many parts of the state”, generally sitting 6C to 12C above the September average. asserted
temperatures → record → average
“It was quite warm compared to the September average in Sydney, say, by more than 10C,” they said, noting the average September maximum for Observatory Hill is 20.1C, and 23.5C for Penrith. asserted
maximum → compare → Penrith
The hot, dry and windy conditions ahead of the southerly change prompted authorities to issue high to extreme fire danger warnings for Monday, particularly for the Greater Hunter, much of the north-eastern parts of the state, and northern inland areas. asserted
conditions → prompt → state
For now, Sydneysiders can now expect a much cooler, wetter outlook for the coming days under the influence of a cool southerly airstream. “We expect the temperatures to be on the cooler side for tomorrow into Wednesday… together with cloud overcast and light showers,” the bureau spokesperson said. asserted
spokesperson → expect → showers
On Tuesday Sydney city temperatures will hover in the high teens, between 18C – 19C, before slightly warming up to between 22C and 24C on Wednesday. asserted
temperatures → hover → Wednesday
Temperatures will then gradually rise through the rest of the week, before another cooler change arrives next weekend. asserted
change → rise → week
Regional centres including Cessnock, Muswellbrook and Singleton were forecast to reach 35C amid extreme fire risk, according to Weatherzone. uncertain
centres → include → Weatherzone
However, the bureau said fire danger “will abate for much of the state” from Tuesday, in the wake of the cool change arriving. asserted
change → say → wake
A strong El Niño developing in the Pacific Ocean is forecast to peak in late spring or summer and “reach levels above the warmest observed since reliable records began in 1950”, according to the BoM. Climate experts have said El Niño will likely combine with climate change to push global temperatures to record highs in 2027. uncertain
Niño → develop → 2027
In Australia, El Niño events increase the chances of warm and dry weather, upping fire danger in summer – especially in regions that haven’t had much rain recently. asserted
that → increase → rain
Authorities told NSW residents to refer to the state’s rural fire service (RFS) website for the most up to date information regarding local fire risks and warnings. asserted
Authorities → tell → risks
💬Give feedback
🕘History 🎫Support