Summer in Perth means long, sun-filled days, warm weather, and barely any rain. Daytime highs usually sit between 29°C and 32°C (84°F to 90°F), so it’s definitely the hottest stretch of the year. Nights cool off a bit, but the warmth tends to stick around well after sunset.
What really sets Perth’s summer apart? The air stays dry, skies are mostly clear, and humidity rarely becomes a problem. Rainfall almost never interrupts things, so most days just feel hot, not sticky.
Sunshine rules the season, giving you endless bright days to hit the beach, wander the city, or just hang out outside.
Locals rely on the famous afternoon sea breeze, the “Fremantle Doctor,” to make things more comfortable. This wind sweeps in reliably, cooling the city during peak heat and shaping the daily routine for just about everyone.
Typical Summer Temperatures in Perth
During summer, hot, dry conditions take over Perth. You’ll see long, sunny stretches, high afternoon temperatures, and warm nights that sometimes make sleeping without a fan or AC a challenge.
Daily Highs and Lows
In summer, daytime temperatures in Perth usually land between 30 °C and 33 °C (86 °F to 91 °F). January and February can get even hotter, with the mercury sometimes shooting past 40 °C (104 °F).
Those super-hot days aren’t all that rare, so if you’re planning to be outside, it’s smart to prepare for them.
At night, lows often hover around 18 °C to 20 °C (64 °F to 68 °F). Warm nights happen a lot, and sometimes the thermometer doesn’t even dip below 25 °C (77 °F), so evenings can feel a bit muggy, despite the dry climate.
This mix of hot days and warm nights is just classic Perth summer. The city’s spot on the coast helps even out the temperatures, so you don’t get the wild swings you might see further inland.
Temperature Variation During Summer
December starts off a touch cooler, with average highs closer to 29 °C (84 °F). But once January and February hit, the heat peaks, and highs often go past 32 °C (90 °F).
Those months also rack up the most days above 35 °C (95 °F).
Heatwaves sometimes roll in and stick around for a few days. During those times, both the days and nights stay well above normal, with back-to-back days above 40 °C and nights that barely cool off below 25 °C.
The “Fremantle Doctor” brings some relief in the late afternoon, but if you’re further inland, you might miss out and feel the heat even more. Temperature differences between the coast and the suburbs can be pretty noticeable.
Comparison to Other Seasons
Perth’s summer is much hotter and drier than spring or autumn. Spring highs usually sit around 24 °C to 27 °C (75 °F to 81 °F), but summer easily pushes into the 30s.
Autumn cools down slowly, with highs dropping to the mid-20s by May.
Winter is a totally different story. Daytime temperatures average 17 °C to 19 °C (63 °F to 66 °F), and nights can dip below 10 °C (50 °F). Most of the rain falls in winter, which makes the dry summer months feel even more extreme.
Perth’s Mediterranean climate really stands out—you get those hot, dry summers and then mild, wet winters.
Humidity Levels During Summer
Perth’s summer air is usually dry to moderately humid, which honestly makes the heat feel a lot less oppressive than in tropical places. That dry air shapes how you experience both the daytime warmth and the evenings.
Average Humidity Percentage
In summer, Perth’s relative humidity stays pretty low compared to other times of the year. January and February often see readings between 38% and 43%, which are actually the lowest of the year.
December is a bit higher but still nowhere near the muggy levels you’d find mid-year.
Thanks to this dryness, even when it’s 30–32°C, the heat doesn’t feel as stifling as it might elsewhere. Mornings might feel a tad damper, but by afternoon, the air dries out a lot.
Low humidity means you’re less likely to feel sticky or weighed down, but it does have downsides. Dry skin, dehydration, and fire risk can all sneak up on you, so it’s smart to keep water and sunscreen handy.
Humidity Fluctuations by Month
Humidity shifts a bit as summer goes on. December usually sits in the mid‑40% range, since there’s still some leftover moisture from spring.
By January, things dry out more, and relative humidity often drops near 40%.
February is usually the driest, averaging about 38%. That’s when the air feels most parched. Even though the days stay hot, the dry air can make nights feel a bit more comfortable.
If you’re planning outdoor stuff, these month-to-month changes matter. December might bring slightly stickier evenings, while February feels drier, which makes heat waves a bit easier but also bumps up bushfire risk.
Precipitation Patterns and Rainfall
Perth’s summer is basically bone dry, with rain showing up only occasionally. The city’s Mediterranean climate means almost all the rain falls in winter, so summer stays parched.
Rainfall Amounts and Frequency
From December to February, Perth barely gets any rain. December averages about 12 mm, and January and February usually see less than 10 mm each.
Rain falls on just 2–4 days a month, and even then, it’s usually quick and light. Heavy downpours hardly ever happen in summer.
The difference compared to winter is pretty wild. In July, Perth gets around 100 mm of rain over 15 days, making it the wettest month.
| Month | Avg. Rainfall (mm) | Avg. Rainy Days |
|---|---|---|
| December | ~12 | 4 |
| January | ~7 | 2 |
| February | ~8 | 2 |
| July | ~100 | 15 |
Probability of Wet Days
The odds of running into a rainy day in summer are tiny. In January and February, there’s usually less than a 10% chance of measurable rain on any given day.
So, you can count on long, dry stretches with almost no interruptions. If it does rain, it’s usually just a quick afternoon shower or a passing coastal system.
In winter, though, the chance of rain shoots up to 50% or more in June and July. That’s something to keep in mind if you’re planning to be outside.
Seasonal Changes in Precipitation
Perth’s rainfall follows a very clear seasonal rhythm. Summer stays dry, while winter brings the rain.
The switch starts in late autumn, when cold fronts off the Indian Ocean bring more frequent showers.
From May through August, rain picks up fast, peaking in July. By September and October, things dry out again, and by November, the long dry season is back.
This pattern shapes daily life—summer means you rarely have to worry about rain, while winter requires more flexibility.
Cloud Cover and Sunshine
In summer, Perth’s skies are mostly clear, with only the occasional cloudy stretch. Sunshine is everywhere, and the season is famous for its long, bright days.
Average Cloud Cover
Cloud cover barely changes through summer. On average, skies are overcast or mostly cloudy just about 17% of the time.
Most days, you’ll wake up to clear or just lightly clouded skies.
The fewest cloudy days happen in mid-January, when clear skies can reach up to 86%. By late February, things get a bit cloudier, but not by much.
Just for reference:
| Month | % of Overcast/Mostly Cloudy Skies |
|---|---|
| December | ~7% |
| January | ~14% |
| February | ~17% |
Perth ranks as one of the sunniest big cities in Australia, so you rarely have to plan around gray skies.
Clear and Overcast Days
Clear days are the norm in summer. January stands out as the brightest month, with 10 to 11 hours of sunshine most days.
That makes it easy to plan beach trips or day hikes without worrying about the weather.
Overcast days don’t come around much, and even when they do, they usually bring mild weather instead of heavy rain. On those cloudier days, the chance of rain stays low, usually between 4% and 7%.
If you want the best shot at perfect weather, aim for mid to late January. During that stretch, skies are clear or mostly clear for more than 80% of days.
Wind Conditions in Perth’s Summer
Perth’s summer is breezy, and the winds play a big part in shaping the weather and your outdoor plans. You’ll notice steady ocean breezes and some stronger gusts inland that affect temperature, comfort, and even air quality.
Prevailing Winds and Breezes
Every summer afternoon, you’ll feel the sea breeze—locals call it the Fremantle Doctor. It blows in from the southwest, usually after midday.
Speeds often hit 20–25 km/h (12–15 mph), and on windier days, it can get up to 30 km/h (18 mph).
This breeze cools things down after hot mornings. Without it, temperatures can soar past 35°C, but with it, you’ll notice a big drop, especially by the coast.
Mornings tend to be calmer, with winds out of the east or northeast. Those breezes feel hotter and drier, bringing in warm air from inland. When the sea breeze kicks in later, it’s cooler and a bit more humid, so you feel a real shift in comfort.
Impact of Wind on Weather
Wind really changes how you experience Perth’s summer. The sea breeze can keep coastal areas much cooler during heat waves, but inland suburbs sometimes miss out and stay much hotter.
You might see a 5–7°C difference between the coast and further inland on the same day.
Wind also helps clear the air, blowing away haze and pollution. On calm days, smoke or dust can linger, making things less pleasant. For outdoor stuff like cycling, sailing, or kitesurfing, those regular afternoon winds are a real plus.
Late spring and early summer can bring gustier periods, with average speeds hitting 7 m/s (25 km/h). These winds can bend small trees and send loose stuff flying, so it’s smart to secure outdoor setups.
Daylight Hours and Sun Exposure
Perth summers bring long days and strong sunlight. You get plenty of bright hours, which is great for outdoor plans—but you’ll need to think about sun protection, too.
Length of Days
In December and January, Perth enjoys some of Australia’s longest days, with about 14 hours of daylight.
On average, summer brings 10 to 11 hours of sunshine daily. That puts Perth among the sunniest capitals anywhere.
Winter, by contrast, offers less than 6 hours of sunshine per day, so the summer brightness really stands out.
All that sunlight means UV levels often reach extreme highs. If you’re outside for long, sunscreen, hats, and sunglasses are a must.
The extra daylight is a bonus for tourism and recreation. You can squeeze in beach trips, hikes, or evening events and still have plenty of sunlight left.
Sunrise and Sunset Times
In summer, the sun usually rises in Perth between 5:00 a.m. and 5:30 a.m.. Mornings brighten fast, which is great if you’re into early exercise or just want to get moving before the heat kicks in.
Sunsets come pretty late, landing between 7:15 p.m. and 7:45 p.m. during December and January. That extra evening light? It really lets you squeeze in a coastal walk, some outdoor sports, or maybe even a relaxed dinner outside after work.
You can count on these daylight patterns to stay pretty steady. Planning day trips feels a lot easier when you know the sun won’t disappear too soon.
Perth sits right on the west coast, so you get these amazing sunsets over the Indian Ocean. Honestly, a lot of people end up timing their evenings just to catch that view.