Average Weather in Perth Australia
In Perth, the summers are warm and dry; the winters are long, cool, and wet; and it is windy and mostly clear year round. Over the course of the year, the temperature typically varies from 48°F to 86°F and is rarely below 40°F or above 97°F.
Based on the tourism score, the best time of year to visit Perth for warm-weather activities is from late November to late March.
The hot season lasts for 3.0 months, from December 20 to March 21, with an average daily high temperature above 82°F. The hottest day of the year is February 11, with an average high of 86°F and low of 65°F.
The cool season lasts for 4.0 months, from May 26 to September 27, with an average daily high temperature below 68°F. The coldest day of the year is July 19, with an average low of 48°F and high of 63°F.
Average High and Low Temperature
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, 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 Perth, the average percentage of the sky covered by clouds experiences mild seasonal variation over the course of the year.
The clearer part of the year in Perth begins around August 18 and lasts for 7.0 months, ending around March 18. On January 19, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 86% of the time, and overcast or mostly cloudy 14% of the time.
The cloudier part of the year begins around March 18 and lasts for 5.0 months, ending around August 18. On April 23, the cloudiest day of the year, the sky is overcast or mostly cloudy 31% of the time, and clear, mostly clear, or partly cloudy 69% of the time.
Cloud Cover Categories
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Perth varies significantly throughout the year.
The wetter season lasts 4.6 months, from May 9 to September 28, with a greater than 23% chance of a given day being a wet day. The chance of a wet day peaks at 42% on July 22.
The drier season lasts 7.4 months, from September 28 to May 9. The smallest chance of a wet day is 3% on December 30.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 42% on July 22.
Daily Chance of Precipitation
To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Perth experiences extreme seasonal variation in monthly rainfall.
The rainy period of the year lasts for 10 months, from January 16 to November 29, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around July 7, with an average total accumulation of 4.7 inches.
The rainless period of the year lasts for 1.6 months, from November 29 to January 16. The least rain falls around December 22, with an average total accumulation of 0.3 inches.
Average Monthly Rainfall
The length of the day in Perth varies significantly over the course of the year. In 2018, the shortest day is June 21, with 10 hours, 3 minutes of daylight; the longest day is December 22, with 14 hours, 15 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:03 AM on December 4, and the latest sunrise is 2 hours, 15 minutes later at 7:17 AM on July 1. The earliest sunset is at 5:18 PM on June 11, and the latest sunset is 2 hours, 8 minutes later at 7:26 PM on January 8.
Daylight saving time (DST) is not observed in Perth during 2018.
Sunrise & Sunset with Twilight
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 perceived humidity level in Perth, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, staying within 4% of 4% throughout.
Humidity Comfort Levels
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 Perth experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 4.7 months, from October 31 to March 21, with average wind speeds of more than 12.8 miles per hour. The windiest day of the year is January 23, with an average hourly wind speed of 14.2 miles per hour.
The calmer time of year lasts for 7.3 months, from March 21 to October 31. The calmest day of the year is May 2, with an average hourly wind speed of 11.4 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Perth varies throughout the year.
The wind is most often from the east for 3.5 months, from February 23 to June 9, with a peak percentage of 43% on March 6. The wind is most often from the west for 3.7 months, from June 9 to October 1, with a peak percentage of 42% on September 7. The wind is most often from the south for 4.8 months, from October 1 to February 23, with a peak percentage of 51% on January 1.
Perth is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.
The average water temperature experiences some seasonal variation over the course of the year.
The time of year with warmer water lasts for 3.9 months, from January 15 to May 12, with an average temperature above 71°F. The day of the year with the warmest water is March 7, with an average temperature of 72°F.
The time of year with cooler water lasts for 3.2 months, from July 30 to November 7, with an average temperature below 67°F. The day of the year with the coolest water is September 25, with an average temperature of 65°F.
Average Water Temperature
Best Time of Year to Visit
To characterize how pleasant the weather is in Perth throughout the year, we compute two travel scores.
The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Perth for general outdoor tourist activities is from late November to late March, with a peak score in the third week of January.
The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Perth for hot-weather activities is from early January to early March, with a peak score in the second week of February.
For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.
Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.
Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.
Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.
Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.
Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).
Temperatures in Perth are sufficiently warm year round that it is not entirely meaningful to discuss the growing season in these terms. We nevertheless include the chart below as an illustration of the distribution of temperatures experienced throughout the year.
Time Spent in Various Temperature Bands and the Growing Season
Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.
Growing Degree Days
This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.
The average daily incident shortwave solar energy experiences extreme seasonal variation over the course of the year.
The brighter period of the year lasts for 3.4 months, from November 4 to February 17, with an average daily incident shortwave energy per square meter above 7.6 kWh. The brightest day of the year is December 28, with an average of 8.8 kWh.
The darker period of the year lasts for 3.6 months, from May 2 to August 21, with an average daily incident shortwave energy per square meter below 3.9 kWh. The darkest day of the year is June 23, with an average of 2.6 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Perth are -31.952 deg latitude, 115.861 deg longitude, and 69 ft elevation.
The topography within 2 miles of Perth contains only modest variations in elevation, with a maximum elevation change of 325 feet and an average elevation above sea level of 66 feet. Within 10 miles also contains only modest variations in elevation (459 feet). Within 50 miles contains only modest variations in elevation (2,005 feet).
The area within 2 miles of Perth is covered by artificial surfaces (52%), sparse vegetation (19%), trees (14%), and water (13%), within 10 miles by artificial surfaces (51%) and trees (19%), and within 50 miles by water (37%) and trees (28%).
This report illustrates the typical weather in Perth, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There are 2 weather stations near enough to contribute to our estimation of the temperature and dew point in Perth.
For each station, the records are corrected for the elevation difference between that station and Perth according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
The estimated value at Perth is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Perth and a given station.
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , by Jean Meeus.
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.
Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.
Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.
Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .
Time zones for aiports and weather stations are provided by AskGeo.com .
Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.
The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.
We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.
We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.