Climate and average weather in Hornsby
In Hornsby, the summers are hot, showery, and partly cloudy and the winters are mild and mostly clear.
Over the course of the year, the temperature in Hornsby typically varies from 7°C to 28°C, and is rarely below 3°C or above 35°C. January is the hottest month of the year, while July is the coldest.
Based on the travel score, the best times of year to visit Hornsby for warm-weather activities are from early February to mid June and late June to late December.
- Hottest
- Jan
- 28°
- Coldest
- Jul
- 7°
- Wettest
- Feb
- 84 mm
- Driest
- Jul
- 35 mm
- Rain / yr
- 654 mm
- 93 wet days
- Daylight
- 9.8–14.2 h
- shortest–longest
- Elevation
- 186 m
- 33.7°S
- Clearest
- Aug
- 33% cloud
Hornsby is suburb of Sydney, New South Wales, Australia.
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Hornsby weather by month, at a glance
The whole year in one picture — sky, rain, humidity, temperature and travel score. Click any band to jump to its full chart.
Each stripe is one measure across the whole year, stacked so a single day reads top to bottom. The sky band runs overcast grey on top down to clear blue at the base — more blue means sunnier — followed by the rainfall curve, the humidity band, a temperature strip that tints each stretch of the year by how warm its average high is, and the travel-score line at the foot. Scan straight down any date to read that day across every measure at once; the score climbs highest around late June to late December.
Temperature through the year
Daily average highs and lows in Hornsby, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
The hot season lasts 4.0 months, from November 22 to March 22, with daily high temperatures above 25°C. The hottest month of the year in Hornsby is January, with an average high of 28°C and low of 19°C.
The cool season lasts 2.9 months, from May 26 to August 22, with daily high temperatures below 19°C. The coldest month of the year in Hornsby is July, with an average low of 7°C and high of 17°C.
Days typically run about 10°C warmer than nights, with the widest day–night swing (around 12°C) in September.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 28 | 27 | 26 | 23 | 20 | 18 | 17 | 19 | 22 | 24 | 25 | 27 |
| Avg low (°C) | 19 | 19 | 17 | 13 | 10 | 8 | 7 | 7 | 10 | 13 | 15 | 17 |
| Avg high (°C) | Avg low (°C) | |
|---|---|---|
| Jan | 28 | 19 |
| Feb | 27 | 19 |
| Mar | 26 | 17 |
| Apr | 23 | 13 |
| May | 20 | 10 |
| Jun | 18 | 8 |
| Jul | 17 | 7 |
| Aug | 19 | 7 |
| Sep | 22 | 10 |
| Oct | 24 | 13 |
| Nov | 25 | 15 |
| Dec | 27 | 17 |
Average hourly temperature in Hornsby
A compact picture of the whole year, hour by hour: each column is a day, each row an hour, and the color is the modeled average temperature. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
Read left to right for the day of the year and top to bottom for the hour of the day; the color is the modeled temperature, cool blues through to hot reds on the same scale as the other charts. A vertical slice is a single day's swing — coolest just before dawn, warmest in the mid-afternoon — while a horizontal slice follows one hour across the seasons. The darker overlay marks night and the lighter one the twilight around sunrise and sunset. Colors run warmest on January afternoons, near 28°C, and coldest before dawn in July, near 7°C.
Hornsby weather by month
Every month at a glance. Click a month for its detailed page.
| 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 | 13.7 | 7.0 |
| Dec | 27° / 17° | 58 | 8.7 | 14.2 | 6.7 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Hornsby gets about 654 mm of precipitation a year. On a typical day the chance of rain is some rain, but that rises and falls sharply with the seasons.
The wetter season lasts 5.6 months, from around Oct 27 to Apr 13, peaking in February at about 36% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Aug 7.
February is the wettest month by volume, with 84 mm over about 10 wet days; July is the driest, with 35 mm.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain on a day (%) | 30 | 35 | 34 | 26 | 21 | 24 | 19 | 17 | 20 | 24 | 28 | 28 |
| Rain days | 9 | 10 | 11 | 8 | 6 | 7 | 6 | 5 | 6 | 7 | 9 | 9 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 30 | 9 |
| Feb | 35 | 10 |
| Mar | 34 | 11 |
| Apr | 26 | 8 |
| May | 21 | 6 |
| Jun | 24 | 7 |
| Jul | 19 | 6 |
| Aug | 17 | 5 |
| Sep | 20 | 6 |
| Oct | 24 | 7 |
| Nov | 28 | 9 |
| Dec | 28 | 9 |
Monthly rainfall
Over a full year, Hornsby collects about 654 mm of rain across 93 wet days — roughly 54 mm in an average month.
It doesn’t fall evenly. February is the wettest month with 84 mm, while July is the driest at just 35 mm. The three wettest months alone bring about 33% of the year’s total.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rainfall (mm) | 66 | 84 | 66 | 51 | 45 | 61 | 35 | 35 | 39 | 49 | 66 | 58 |
| Rain days | 9 | 10 | 11 | 8 | 6 | 7 | 6 | 5 | 6 | 7 | 9 | 9 |
| Rainfall (mm) | Rain days | |
|---|---|---|
| Jan | 66 | 9 |
| Feb | 84 | 10 |
| Mar | 66 | 11 |
| Apr | 51 | 8 |
| May | 45 | 6 |
| Jun | 61 | 7 |
| Jul | 35 | 6 |
| Aug | 35 | 5 |
| Sep | 39 | 6 |
| Oct | 49 | 7 |
| Nov | 66 | 9 |
| Dec | 58 | 9 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Hornsby, the average share of the sky covered by clouds shows significant seasonal variation over the course of the year.
The clearer part of the year begins around June 14 and lasts for 4.1 months, ending around October 16. The clearest month is August, when the sky is clear, mostly clear, or partly cloudy 78% of the time on average.
The cloudier part of the year begins around October 17 and lasts for 5.4 months, ending around March 29. The cloudiest month is December, when it is overcast or mostly cloudy 52% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 51 | 49 | 55 | 63 | 66 | 64 | 74 | 78 | 72 | 60 | 49 | 48 |
| Cloudier (%) | 49 | 51 | 45 | 37 | 34 | 36 | 26 | 22 | 28 | 40 | 51 | 52 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 51 | 49 |
| Feb | 49 | 51 |
| Mar | 55 | 45 |
| Apr | 63 | 37 |
| May | 66 | 34 |
| Jun | 64 | 36 |
| Jul | 74 | 26 |
| Aug | 78 | 22 |
| Sep | 72 | 28 |
| Oct | 60 | 40 |
| Nov | 49 | 51 |
| Dec | 48 | 52 |
Daylight, sunrise and sunset
Hours of daylight through the year, with sunrise and sunset times.
The gold band is daylight — sunrise runs along its lower edge, sunset along the upper — so it widens toward summer and pinches toward winter, with night the dark area above and below. The longest day, around January 1, brings about 14 h 12 min of light; the shortest, around June 7, only 9 h 48 min — a swing of roughly 4 h 24 min.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 14.0 | 13.3 | 12.3 | 11.2 | 10.3 | 9.8 | 10.0 | 10.7 | 11.8 | 12.8 | 13.7 | 14.2 |
| Sunrise (AM) | 6:05 | 6:33 | 6:57 | 7:21 | 7:44 | 8:03 | 8:02 | 7:38 | 6:56 | 6:15 | 5:48 | 5:45 |
| Sunset (PM) | 8:05 | 7:48 | 7:13 | 6:31 | 6:00 | 5:49 | 6:00 | 6:22 | 6:44 | 7:06 | 7:34 | 7:59 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 14.0 | 6:05 | 8:05 |
| Feb | 13.3 | 6:33 | 7:48 |
| Mar | 12.3 | 6:57 | 7:13 |
| Apr | 11.2 | 7:21 | 6:31 |
| May | 10.3 | 7:44 | 6:00 |
| Jun | 9.8 | 8:03 | 5:49 |
| Jul | 10.0 | 8:02 | 6:00 |
| Aug | 10.7 | 7:38 | 6:22 |
| Sep | 11.8 | 6:56 | 6:44 |
| Oct | 12.8 | 6:15 | 7:06 |
| Nov | 13.7 | 5:48 | 7:34 |
| Dec | 14.2 | 5:45 | 7:59 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Hornsby averages about 13 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 9 and 20 days.
The sunnier stretch runs 5.9 months, from around Apr 14 to Oct 11. The sunniest month is August, with roughly 19 sunny days (bright).
The greyest month is November, down near 9 sunny days — about 52% fewer than the August peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 11 | 9 | 11 | 13 | 15 | 15 | 18 | 19 | 16 | 13 | 9 | 10 |
| Sky | Mixed | Mixed | Mixed | Mixed | Mixed | Mixed | Bright | Bright | Bright | Mixed | Mixed | Mixed |
| Sunny days | Sky | |
|---|---|---|
| Jan | 11 | Mixed |
| Feb | 9 | Mixed |
| Mar | 11 | Mixed |
| Apr | 13 | Mixed |
| May | 15 | Mixed |
| Jun | 15 | Mixed |
| Jul | 18 | Bright |
| Aug | 19 | Bright |
| Sep | 16 | Bright |
| Oct | 13 | Mixed |
| Nov | 9 | Mixed |
| Dec | 10 | Mixed |
Humidity comfort
Share of days at each humidity comfort level, based on the dew point — the measure that tracks how muggy it actually feels.
Humidity comfort is graded by the dew point — the temperature at which the air would be fully saturated — because it tracks how muggy it actually feels far better than relative humidity does. A low dew point feels dry and crisp; a high one feels sticky and oppressive no matter the reading on a humidity gauge.
In Hornsby, how humid it feels changes dramatically over the year.
The more humid part of the year lasts 4.6 months, from around November 19 to April 6. The muggiest month is January, when the air feels humid, muggy or worse about 71% of the time.
The most comfortable stretch runs from around April 7 to November 18, and June is the most comfortable month — the air is dry or comfortable 100% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 11 | 6 | 15 | 45 | 83 | 96 | 99 | 99 | 91 | 72 | 44 | 23 |
| Comfortable (%) | 19 | 18 | 28 | 37 | 14 | 4 | 1 | 1 | 8 | 22 | 33 | 29 |
| Humid (%) | 36 | 37 | 40 | 16 | 3 | 0 | 0 | 0 | 1 | 6 | 20 | 35 |
| Muggy (%) | 31 | 35 | 16 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 3 | 13 |
| Oppressive (%) | 3 | 4 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | Oppressive (%) | |
|---|---|---|---|---|---|
| Jan | 11 | 19 | 36 | 31 | 3 |
| Feb | 6 | 18 | 37 | 35 | 4 |
| Mar | 15 | 28 | 40 | 16 | 1 |
| Apr | 45 | 37 | 16 | 1 | 0 |
| May | 83 | 14 | 3 | 0 | 0 |
| Jun | 96 | 4 | 0 | 0 | 0 |
| Jul | 99 | 1 | 0 | 0 | 0 |
| Aug | 99 | 1 | 0 | 0 | 0 |
| Sep | 91 | 8 | 1 | 0 | 0 |
| Oct | 72 | 22 | 6 | 0 | 0 |
| Nov | 44 | 33 | 20 | 3 | 0 |
| Dec | 23 | 29 | 35 | 13 | 0 |
Wind
Average wind speed through the year, banded into plain-language speed zones so a number reads as 'breezy' or 'calm' without knowing the scale.
This is the average sustained wind speed at the standard 10 metres above open ground — the steady flow a weather station reports, not the sharper gusts that come and go, which can run half again as fast. It's the number that says whether a place is generally breezy or calm.
Wind in Hornsby is steady company: average speeds sit near 10 km/h — calm — in every month of the year, with no meaningful windy or calm season.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (km/h) | 11 | 11 | 10 | 9 | 9 | 10 | 10 | 11 | 11 | 11 | 11 | 11 |
| Feels | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm |
| Wind speed (km/h) | Feels | |
|---|---|---|
| Jan | 11 | calm |
| Feb | 11 | calm |
| Mar | 10 | calm |
| Apr | 9 | calm |
| May | 9 | calm |
| Jun | 10 | calm |
| Jul | 10 | calm |
| Aug | 11 | calm |
| Sep | 11 | calm |
| Oct | 11 | calm |
| Nov | 11 | calm |
| Dec | 11 | calm |
Hazard calendar for Hornsby
When the seasonal hazards worth planning around — the rainy season, tropical-cyclone risk and dust haze — are active through the year.
Hornsby sits in the South Indian Ocean cyclone belt; the season peaks January–March.
Best time to visit Hornsby
To characterize how pleasant the weather is in Hornsby throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
Around late December, Hornsby is still near the tail of its best-weather window — great conditions with the peak-season crowds already thinning.
Inferred from the travel-score curve; month-by-month visitor numbers are a planned addition.
The travel score favors clear, rainless days with daytime highs between 18°C and 28°C. Based on this score, the best time of year to visit Hornsby for general outdoor tourist activities is from early February to mid January, with a peak score in the last week of September.
The travel score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Travel score (0–10) | 6.3 | 6.3 | 6.8 | 7.3 | 7.1 | 6.3 | 6.5 | 7.2 | 7.5 | 7.5 | 7.1 | 6.7 |
| Rating | good | good | good | good | good | good | good | good | good | ideal | good | good |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 6.3 | good |
| Feb | 6.3 | good |
| Mar | 6.8 | good |
| Apr | 7.3 | good |
| May | 7.1 | good |
| Jun | 6.3 | good |
| Jul | 6.5 | good |
| Aug | 7.2 | good |
| Sep | 7.5 | good |
| Oct | 7.5 | ideal |
| Nov | 7.1 | good |
| Dec | 6.7 | good |
The beach/pool score favors clear, rainless days with daytime highs between 24°C and 34°C. Based on this score, the best time of year to visit Hornsby for hot-weather activities is from late September to mid April, with a peak score in the second week of January.
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
What to pack for Hornsby, by month
Month by month, what's worth putting in the bag — from the temperature range, rain chance, sun and wind. Tap a month for a quick packing note.
For a warm-season trip around January (highs near 28°C), the essentials are light clothes, rain gear and sun protection. In the cold season around July (highs near 17°C), pack a warm layer.
In January, Hornsby sees daytime highs around 28°C and nights near 19°C. Pack light clothes and sun protection. Worth having: rain gear. About 9 days see rain.
Sea temperature near Hornsby
Average ocean temperature at the nearest coast, month by month, banded into swim-comfort zones — the other half of the beach question.
The sea at the nearest coast (about 27 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 (midday) in Hornsby by month
Clear-sky midday UV index through the year, shaded by the WHO exposure levels — how much sun protection each month calls for.
Under clear skies, the midday UV index in Hornsby 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 |
Average hourly UV index in Hornsby
Modeled clear-sky UV for every hour of every day — when in the day sun protection actually matters.
The whole year hour by hour: each column is a day, each row an hour, and the color is the modeled clear-sky UV index — the midday peak scaled down as the sun sits lower in the sky. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
UV falls off far faster than brightness as the sun drops, so even in January the burn window is concentrated in the middle of the day: about 9 hours a day reach index 3 (protection recommended), and 6.5 hours reach 6 or more. Mornings and late afternoons stay comparatively gentle year round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV ≥ 3 (h/day) | 9 | 8.5 | 7 | 5.5 | 2.5 | 0 | 0 | 4 | 5.5 | 7 | 8 | 9 |
| UV ≥ 6 (h/day) | 6.5 | 6 | 4.5 | 0 | 0 | 0 | 0 | 0 | 0 | 4 | 5.5 | 6.5 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 9 | 6.5 |
| Feb | 8.5 | 6 |
| Mar | 7 | 4.5 |
| Apr | 5.5 | 0 |
| May | 2.5 | 0 |
| Jun | 0 | 0 |
| Jul | 0 | 0 |
| Aug | 4 | 0 |
| Sep | 5.5 | 0 |
| Oct | 7 | 4 |
| Nov | 8 | 5.5 |
| Dec | 9 | 6.5 |
Air quality in Hornsby by month
Average fine-particle pollution (PM2.5) through the year — so you can see which months the air is worst, not just the yearly average.
Air quality in Hornsby 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 |
Growing season
Hornsby is frost-free year round — even the coldest nights rarely reach freezing, so there is no start or end to the growing season.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Frost-free chance (%) | 100 | 100 | 100 | 100 | 100 | 99 | 98 | 99 | 100 | 100 | 100 | 100 |
| Frost nights | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Frost-free chance (%) | Frost nights | |
|---|---|---|
| Jan | 100 | 0 |
| Feb | 100 | 0 |
| Mar | 100 | 0 |
| Apr | 100 | 0 |
| May | 100 | 0 |
| Jun | 99 | 0 |
| Jul | 98 | 0 |
| Aug | 99 | 0 |
| Sep | 100 | 0 |
| Oct | 100 | 0 |
| Nov | 100 | 0 |
| Dec | 100 | 0 |
Growing degree days
Growing degree days tally heat above 10°C: each day adds however many degrees its average temperature runs over that threshold, and cold days add nothing. Hornsby banks about 2,831 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around January.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Growing degree days (°C·days) | 413 | 360 | 345 | 244 | 156 | 81 | 59 | 93 | 168 | 247 | 296 | 367 |
| Growing degree days (°C·days) | |
|---|---|
| Jan | 413 |
| Feb | 360 |
| Mar | 345 |
| Apr | 244 |
| May | 156 |
| Jun | 81 |
| Jul | 59 |
| Aug | 93 |
| Sep | 168 |
| Oct | 247 |
| Nov | 296 |
| Dec | 367 |
Solar energy
Average daily shortwave solar energy reaching the ground, banded into brightness zones so the number means something at a glance.
Solar energy is how much sunlight actually reaches the ground each day, measured in kilowatt-hours per square metre (kWh/m²) — the combined effect of how long the sun is up, how high it climbs, and how much cloud gets in the way. It's the raw fuel a solar panel has to work with: for scale, 1 kWh/m² a day is dim and wintry, while 7+ is desert-bright.
Hornsby receives about 4.7 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 2.5 and 6.9 kWh/m².
The brighter stretch of the year lasts 6.2 months, from around Sep 10 to Mar 17. The brightest month is December, averaging about 6.6 kWh/m² (intense).
The dimmest month is June, down near 2.5 kWh/m² — roughly 62% less than the December peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 6.5 | 5.5 | 4.7 | 3.9 | 3.0 | 2.5 | 2.9 | 3.8 | 4.9 | 5.8 | 6.2 | 6.5 |
| Level | Intense | Bright | Bright | Moderate | Moderate | Moderate | Moderate | Moderate | Bright | Bright | Intense | Intense |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 6.5 | Intense |
| Feb | 5.5 | Bright |
| Mar | 4.7 | Bright |
| Apr | 3.9 | Moderate |
| May | 3.0 | Moderate |
| Jun | 2.5 | Moderate |
| Jul | 2.9 | Moderate |
| Aug | 3.8 | Moderate |
| Sep | 4.9 | Bright |
| Oct | 5.8 | Bright |
| Nov | 6.2 | Intense |
| Dec | 6.5 | Intense |
Where is Hornsby?
Hornsby sits at 33.7°S, 151.1°E, 186 m above sea level, in Australia. The nearest listed city is Wahroonga, 2.0 km away.
Topography around Hornsby
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Hornsby.
Within 3 km, the terrain around Hornsby has only modest variations in elevation — a maximum elevation change of 180 m around an average of 167 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 254 m; within 80 km, large variations in elevation — a maximum elevation change of 1,136 m.
The land around Hornsby is covered by trees (80%) within 3 km, trees (76%) within 16 km, and trees (58%) and water (29%) 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 Hornsby (-33.7024°, 151.0993°, elevation 186 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. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).