September Weather Averages for Sydney, Australia

Sydney Australia Weather in September

Sydney / November 13, 2018

The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on September. The horizontal axis is the day, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Average Hourly Temperature in September

The average hourly temperature, color coded into bands: frigid < 15°F < freezing < 32°F < chilly < 45°F < cold < 55°F < cool < 65°F < comfortable < 75°F < warm < 85°F < hot < 95°F < sweltering. The shaded overlays indicate night and civil twilight.

The month of September in Sydney experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 24% throughout the month.

The clearest day of the month is September 3, with clear, mostly clear, or partly cloudy conditions 77% of the time.

For reference, on November 22, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 38%, while on August 13, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 80%.

Cloud Cover in September

The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds: clear < 20% < mostly clear < 40% < partly cloudy < 60% < mostly cloudy < 80% < overcast.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Sydney, the chance of a wet day over the course of September is essentially constant, remaining around 18% throughout.

For reference, the year's highest daily chance of a wet day is 30% on January 31, and its lowest chance is 16% on August 13.

Probability of Precipitation in September

The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

Rainfall

To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.

The average sliding 31-day rainfall during September in Sydney is essentially constant, remaining about 1.9 inches throughout, and rarely exceeding 4.7 inches or falling below 0.2 inches.

The lowest average 31-day accumulation is 1.8 inches on September 4.

Average Monthly Rainfall in September

The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average liquid-equivalent snowfall.

Over the course of September in Sydney, the length of the day is increasing. From the start to the end of the month, the length of the day increases by 60 minutes, implying an average daily increase of 2 minutes, 4 seconds, and weekly increase of 14 minutes, 26 seconds.

The shortest day of the month is September 1, with 11 hours, 23 minutes of daylight and the longest day is September 30, with 12 hours, 23 minutes of daylight.

Hours of Daylight and Twilight in September

The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The latest sunrise of the month in Sydney is 6:13 AM on September 1 and the earliest sunrise is 40 minutes earlier at 5:33 AM on September 30.

The earliest sunset is 5:37 PM on September 1 and the latest sunset is 20 minutes later at 5:57 PM on September 30.

Daylight saving time is observed in Sydney during 2017, but it neither starts nor ends during September, so the entire month is in standard time.

For reference, on December 21, the longest day of the year, the Sun rises at 5:40 AM and sets 14 hours, 25 minutes later, at 8:05 PM, while on June 21, the shortest day of the year, it rises at 6:59 AM and sets 9 hours, 54 minutes later, at 4:53 PM.

Sunrise & Sunset with Twilight and Daylight Saving Time in September

The solar day over the course of September. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray.

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

The chance that a given day will be muggy in Sydney is essentially constant during September, remaining around 0% throughout.

For reference, on February 5, the muggiest day of the year, there are muggy conditions 41% of the time, while on June 8, the leasy muggy day of the year, there are muggy conditions 0% of the time.

Humidity Comfort Levels in September

The percentage of time spent at various humidity comfort levels, categorized by dew point: dry < 55°F < comfortable < 60°F < humid < 65°F < muggy < 70°F < oppressive < 75°F < miserable.

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Sydney is essentially constant during September, remaining within 0.1 miles per hour of 4.3 miles per hour throughout.

For reference, on August 2, the windiest day of the year, the daily average wind speed is 4.5 miles per hour, while on April 8, the calmest day of the year, the daily average wind speed is 4.0 miles per hour.

Average Wind Speed in September

The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The wind direction in Sydney during September is predominantly out of the west from September 1 to September 23 and the north from September 23 to September 30.

Source: weatherspark.com