Castle Hill in Winter
In winter (June, July and August), Castle Hill sees average daytime highs around 18°C and overnight lows near 7°C, with 131 mm of rain over about 18 wet days across the season. It is the coldest season of the year and the driest season of the year.
Across winter, daytime highs hold fairly steady around 18°C. The sky is clear or mostly clear about 57% of the time across winter, and the air most often feels dry.
Winter is Castle Hill's 3rd-best season to visit on our travel score. For the whole year in context, see Castle Hill's year-round climate.
- Avg daytime high
- 18°C
- coldest season of the year
- Avg overnight low
- 7°C
- Rainfall
- 131 mm
- 18 wet days
- Avg wind
- 10 km/h
- Travel score
- 6.7
- 3rd-best season
- Months
- Jun · Jul · Aug
Temperature in Castle Hill in Winter
Across winter, daytime highs hold fairly steady around 18°C.
A typical winter day in Castle Hill reaches about 18°C and drops to 7°C overnight. The warmest of the three months is August, the coolest July.
Castle Hill weather by month
How the three winter months (June, July and August) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 28° / 19° | 66 | 9.1 | 14 | 6.2 |
| Feb | 27° / 19° | 84 | 10 | 13.3 | 6.3 |
| Mar | 26° / 17° | 66 | 10.6 | 12.3 | 6.8 |
| Apr | 23° / 13° | 51 | 7.8 | 11.2 | 7.4 |
| May | 20° / 10° | 45 | 6.3 | 10.3 | 7.1 |
| Jun | 18° / 8° | 61 | 7.4 | 9.8 | 6.3 |
| Jul | 17° / 7° | 35 | 5.7 | 10 | 6.5 |
| Aug | 19° / 7° | 35 | 5.2 | 10.7 | 7.2 |
| Sep | 22° / 10° | 39 | 6.1 | 11.8 | 7.5 |
| Oct | 24° / 13° | 49 | 7.3 | 12.8 | 7.5 |
| Nov | 25° / 15° | 66 | 8.6 | 13.8 | 7.0 |
| Dec | 27° / 17° | 58 | 8.7 | 14.2 | 6.7 |
Cloud cover in Winter
The sky is clear or mostly clear about 57% of the time across winter.
Chance of precipitation in Winter
Castle Hill gets around 131 mm of rain over 18 wet days across winter. The line is the day-by-day chance of measurable precipitation.
Humidity in Winter
Most of winter feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Winter
Winds average 10 km/h across winter.
Sunrise & sunset in Winter
Daylight runs from about 9 h 54 min in early June to 11 h 12 min by late August. The lit band spans sunrise to sunset each day.
Solar energy in Winter
Average shortwave solar energy reaching the ground each day across winter, about 3.0 kWh/m².
Hazard calendar for Castle Hill
None of Castle Hill's seasonal hazards peak in winter. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do.
Castle Hill sits in the South Indian Ocean cyclone belt; the season peaks January–March.
Is winter a good time to visit Castle Hill?
Our two travel scores rate winter for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
winter is a reasonable time to visit Castle Hill for sightseeing.
What to pack for Castle Hill in Winter
From winter's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In winter, Castle Hill sees daytime highs around 18°C and nights near 7°C. Worth packing: a warm layer. About 18 days see rain.
Sea temperature near Castle Hill in Winter
The nearest coast averages about 19°C across winter — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea at the nearest coast (about 37 km away) is warmest in February at about 23°C and coldest in August near 18°C.
It's comfortable for a long swim from Nov 16 to Jun 4 — about 6.6 months when the water holds above 20°C.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 23 | 23 | 23 | 22 | 21 | 20 | 19 | 18 | 18 | 19 | 20 | 21 |
| Comfort | Refreshing | Refreshing | Refreshing | Refreshing | Refreshing | Cool | Cool | Cool | Cool | Cool | Refreshing | Refreshing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 23 | Refreshing |
| Feb | 23 | Refreshing |
| Mar | 23 | Refreshing |
| Apr | 22 | Refreshing |
| May | 21 | Refreshing |
| Jun | 20 | Cool |
| Jul | 19 | Cool |
| Aug | 18 | Cool |
| Sep | 18 | Cool |
| Oct | 19 | Cool |
| Nov | 20 | Refreshing |
| Dec | 21 | Refreshing |
UV index in Castle Hill in Winter
Clear-sky midday UV across winter averages around 3 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Castle Hill peaks around January 16 at about 12 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 19 at about 2 (moderate).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 12 | 11 | 9 | 6 | 4 | 2 | 3 | 4 | 6 | 8 | 10 | 12 |
| Level | Extreme | Extreme | Very high | High | Moderate | Moderate | Moderate | Moderate | High | Very high | Very high | Extreme |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 12 | Extreme |
| Feb | 11 | Extreme |
| Mar | 9 | Very high |
| Apr | 6 | High |
| May | 4 | Moderate |
| Jun | 2 | Moderate |
| Jul | 3 | Moderate |
| Aug | 4 | Moderate |
| Sep | 6 | High |
| Oct | 8 | Very high |
| Nov | 10 | Very high |
| Dec | 12 | Extreme |
Air quality in Castle Hill in Winter
Average fine-particle pollution (PM2.5) through the year — so you can see where winter falls, not just the annual average.
Air quality in Castle Hill is worst in December — around 49 µg/m³ PM2.5 (poor), about 8.1× the cleanest month (June, 6 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 11 | 7 | 7 | 8 | 8 | 6 | 6 | 8 | 10 | 10 | 25 | 49 |
| Level | Good | Good | Good | Good | Good | Good | Good | Good | Good | Good | Moderate | Poor |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 11 | Good |
| Feb | 7 | Good |
| Mar | 7 | Good |
| Apr | 8 | Good |
| May | 8 | Good |
| Jun | 6 | Good |
| Jul | 6 | Good |
| Aug | 8 | Good |
| Sep | 10 | Good |
| Oct | 10 | Good |
| Nov | 25 | Moderate |
| Dec | 49 | Poor |
Where is Castle Hill?
Castle Hill sits at 33.7°S, 151.0°E, 126 m above sea level, in Australia. The nearest listed city is Baulkham Hills, 3.0 km away.
Topography around Castle Hill
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Castle Hill.
Within 3 km, the terrain around Castle Hill has only modest variations in elevation — a maximum elevation change of 139 m around an average of 118 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 251 m; within 80 km, large variations in elevation — a maximum elevation change of 1,191 m.
The land around Castle Hill is covered by trees (64%) and artificial surfaces (31%) within 3 km, trees (55%) and artificial surfaces (32%) within 16 km, and trees (61%) and water (26%) within 80 km.
Australia travel facts
- Travel advisory
- Level 1
- Exercise Normal Precautions
- Power plugs
- Type I
- 230 V · 50 Hz
- Prices
- ≈ 90% of US
- price level, 2025
- GDP per capita
- $65,130
- 2025
- Happiness
- 6.9 / 10
- World Happiness, 2025
- Homicide rate
- 0.9
- per 100k, 2023
- Road deaths
- 4.9
- per 100k/yr, 2019
- Income group
- High
- World Bank
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Castle Hill (-33.7333°, 151°, elevation 126 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google.