Updated 2026-09-25

Solar & Daylight Data

Solar Shading Design: Hobart, Australia

Which months need shading in Hobart, Australia, and how much sun overhangs and fins block on each facade.

On this page

Last updated September 25, 2026 · Location: GeoNames point -42.8794, 147.3294 ([GeoNames AU dump](https://download.geonames.org/export/dump/AU.zip), CC BY 4.0, ID 2163355); time zone Australia/Hobart from the same GeoNames record. Sun positions, sunrise and sunset calculated by Harth with [NOAA's solar calculator equations](https://gml.noaa.gov/grad/solcalc/calcdetails.html), including standard atmospheric refraction, for a sea-level horizon. Sunlight, cloud and air temperature: [NASA POWER climatology](https://power.larc.nasa.gov/docs/services/api/temporal/climatology/) monthly means for 2001–2020 at this point (API v2.10.0, retrieved 2026-09-25).

Direct answer

No month in Hobart averages 18 °C; its warmest three months are January to March (up to 16.6 °C mean). Through them an overhang projecting 0.93 times the window height fully shades a north-facing window at noon. East and west windows get 6.7 hours of direct sun a day, and a P:H 1.0 overhang stops only 42% of it. The warmest month averages 16.6 °C. On the north facade a P:H 1.0 overhang blocks 100% of the warm-month direct sun. Fins with a depth equal to the window width block 28% on each side of the east- and west-facade sun. The south facade gets 2.9 hours of direct sun a day in January to March.

Content and cited inputs reviewed by Harth team · Published 2026-08-26 · Updated 2026-09-25.

Which months need shading in Hobart?

Warm months are those whose NASA POWER mean air temperature is 18 °C or higher. The last column is the overhang projection, as a fraction of window height, that fully shades a north-facing window at solar noon on the 21st.

MonthMean air temp (°C)Warm monthNoon altitudeNorth facade noon P:H
January16.6warmest three67.1°0.42
February16.2warmest three57.7°0.63
March15.2warmest three46.9°0.93
April12.8no35.3°1.41
May10.6no27.0°1.96
June8.9no23.7°2.28
July8.3no26.7°1.99
August8.5no35.0°1.43
September9.7no46.4°0.95
October11.3no57.8°0.63
November13.2no67.0°0.42
December14.9no70.6°0.35

How much warm-month sun each Hobart facade gets, and what blocks it

Averaged over the 21st of each of the three warmest months (January to March). Percentages are the share of the minutes the sun is on that facade during which the device fully shades the glazing. Overhang P:H is projection ÷ window height; fin D:W is fin depth ÷ window width, with a fin on each side.

FacadeDirect sun (h/day)Overhang P:H 0.5Overhang P:H 1.0Fins D:W 1.0Overhang + fins 1.0
North10.440%100%64%100%
North-east8.625%51%39%68%
East6.723%42%28%42%
South-east4.828%45%70%70%
South2.935%54%100%100%
South-west4.828%45%70%70%
West6.723%42%28%42%
North-west8.625%51%39%68%

What this means for shading design in Hobart

The north facade is the easy one: the sun reaches it high in the sky, so a fixed horizontal overhang does most of the work (P:H 1.0 blocks 100% of its warm-month sun). East and west facades take low morning and afternoon sun that passes under any practical overhang; there, fins with D:W 1.0 block 28% on each side, and adjustable external blinds or screens are the dependable answer. The facades that keep the most unblocked sun with both an overhang and fins at 1.0 are east and west.

How these figures were calculated

Sun positions come from NOAA's solar equations at the GeoNames point -42.8794, 147.3294, sampled every 10 minutes from sunrise to sunset on the 21st of each warm month. A facade is sunlit when the sun is above the horizon and in front of it; a device fully shades the window when the vertical shadow angle (overhang) or horizontal shadow angle (fins) exceeds its cut-off angle. Overhangs and fins are assumed to extend well past the window edges, and diffuse sky light, glass type and obstructions are not included. Air temperatures are NASA POWER 2001–2020 monthly means.

Sources and method

Location: GeoNames point -42.8794, 147.3294 (GeoNames AU dump, CC BY 4.0, ID 2163355); time zone Australia/Hobart from the same GeoNames record. Sun positions, sunrise and sunset calculated by Harth with NOAA's solar calculator equations, including standard atmospheric refraction, for a sea-level horizon. Sunlight, cloud and air temperature: NASA POWER climatology monthly means for 2001–2020 at this point (API v2.10.0, retrieved 2026-09-25).

Overhang projection-to-height ratio needed at solar noon by month for Hobart, Australia
Noon overhang ratio by month for Hobart, Australia, plotted from the table above.
Mean air temperature by month for Hobart, Australia
Mean air temperature by month for Hobart, Australia, plotted from the table above.

Frequently asked questions

How deep should a north-facing overhang be in Hobart?

To shade a north-facing window fully at solar noon through Hobart's warm months (January to March), the overhang should project 0.93 times the height from the overhang to the window sill; for a 1.5 m tall window that is about 1.40 m.

Do east and west windows in Hobart need shading?

Rarely for heat, since no month in Hobart averages 18 °C, but for glare they do. In January to March east and west windows in Hobart get about 6.7 hours of direct sun a day, mostly at low angles: a P:H 1.0 overhang blocks only 42% of it, while fins with D:W 1.0 block 28%.

Which months need sun shading in Hobart?

Using NASA POWER 2001–2020 monthly means, no month in Hobart averages 18 °C; the warmest are January to March. The warmest month averages 16.6 °C and the coolest 8.3 °C.

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