September 18 is statistically one of the best days of the year in Sydney. With minimal rain risk (14%) and pleasant highs of 21°C, it's ideal for outdoor adventures. Sydney is seeing high visitor numbers, so iconic spots may be busier than usual.
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Essential Travel Info for Sydney
Currency
AUD
$ Australian dollar
Language
English
Driving
Left side
Connect
See the Sydney district guides for local...
Safety
High Safety
GPI: 1.565
Sydney Weather Forecast for September 18
"Mild & Comfortable. Expect average highs of 20.9°C. 14% chance of rain."
What to Wear in Sydney in September
Based on historical data for September 18, Sydney typically experiences temperatures between 11.3°C and 20.9°C. We recommend packing light jacket, long pants to stay comfortable. Trends suggest it will stay mostly dry (14% rain probability), but checking the forecast before heading out is always wise.
Complete Packing Guide
Weekly breakdown & essential items for Sydney
Smart Suitcase
- Light Jacket
- Long Pants
Average High
20.9°C
Daytime Peak
Average Low
11.3°C
Nighttime Low
Feels Like
21°C
☀️ Feels accurate
Rain Chance
14%
Avg 0.7mm if it rains
Cloud Cover
36%
Overcast
Pressure
1017.5 hPa
Medium volatility
Sydney Weather Conditions & UV Index
Weather Confidence
30-year variance analysis
Based on 10 years of data
✓ Weather is generally predictable, but pack for minor variations. A light backup layer is recommended.
Sun Exposure
UV Index & Safety Guide
Protection Needed
SPF 30 recommended
06:00 - 10:00
16:00 - 18:00
Type I-II
🔴 21 min to burn
Type III-IV
🟡 32 min to burn
Type V-VI
🟢 53 min to burn
UV estimate based on latitude, season & cloud cover. Actual UV may vary.
Outdoor Comfort
How pleasant is it outside?
Dew Point
13.6°C
Pleasant
Heat Stress
Low
No heat warning
😊 Best outdoor time:
Any time during daylight hours
Marine Conditions
Marine Life
No special warnings. Enjoy the swim!
Swim Index
⚠️ Mixed Conditions
Travel & Logistics Insights
Local Calendar
Business Day
Standard hours in Australia
Flight Traffic
Busy
78/100 pressure index
Health Advisory
Required
1 vaccine • View Details →
Landing Slots
~746
Daily arrival options (inc. codeshare)
Sunrise, Sunset & Wind in Sydney
Daylight & Sun
Solar Elevation Cycle
🌅 Sunrise
06:52
☀️ Noon
12:50
🌇 Sunset
18:49
⏱️ Daylight
11h 56m
Wind Speed
19.8 km/h
Gentle breeze
Sunshine
10.1 hrs
Direct Sun (Cloud-free)
Humidity
63%
Slightly humid
Travel Intelligence
Exclusive flight analytics & health data for Sydney
Smart Flight Estimator
Airport-to-Airport Logistics
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Travel Health & Safety in Sydney
Travel Comfort Index
Real-time tourism conditions
Weather Quality
☀️ Excellent
Tourist Crowds
🟡 Busy
Price Level
💰💰💰 Expensive
Health & Wellbeing
Meteo-Health Forecast
Moderate fluctuations. Some sensitivity possible.
Weather unlikely to affect joint pain.
Moderate fish activity expected.
Air quality is excellent. Perfect for outdoor activities.
Regional Safety Profile
Seismic Activity
Zero seismic activity detected in 30 years.
"According to 30YearWeather's analysis of 30 years of NASA satellite data, Sydney on September 18 averages 20.9°C with a 14% precipitation probability. Wedding/Outdoor Event Score: 100/100."
— Source: 30YearWeather.com|Data: NASA POWER (1991-2021)|View Methodology
Sydney Weather History (2010–2024)
Temperature History
Hall of Fame
Records from last 10 years
Compare Other Cities
Same date (September 18) in other destinations
🌍 Explore the same date in different destinations around the world
📍 Is Sydney Worth Visiting on September 18?
Planning a trip to Sydney on September 18? Our historical weather analysis based on 30 years of NASA satellite data shows that this time of year is characterized by pleasant mild weather averaging 20.9°C with a 14% historical precipitation risk.
✈️ Travel Logistics: Approximately 746 landing slots available daily during this period, indicating peak tourist activity.
💉 Health Advisory: 6 vaccinations are recommended for Australia, including COVID-19.
🌊 Coastal Conditions: Water temperature averages 18.8°C (refreshing tonic). Wave conditions are generally fun waves with heights around 1.11m.
📊 Historical Extremes: The hottest September 18 recorded in the last 30 years saw temperatures hit 31.5°C in 2023, while the coldest dropped to 5.6°C in 2017.