The "blue hour" — what it is and how photographers use it
After the sun has set but before full darkness, the sky often turns a deep, saturated blue. This brief window — perhaps 20-40 minutes long — is "blue hour." It's distinct from golden hour (the warm window before sunset) and offers a different aesthetic for photography.
For sunrise/sunset times in any city, the sunrise-sunset page shows them. Blue hour is roughly the period when the sun is 4-8° below the horizon.
What blue hour is
Blue hour is the period when:
- The sun is between 4° and 8° below the horizon
- The sky is deep blue, often saturated
- City lights, vehicles, and buildings are visible (they're now competing with the dimming sky)
- Stars are starting to appear
It happens twice daily: after sunset and before sunrise.
The physics
The deep blue color is produced by a specific atmospheric effect:
1. The sun is below the horizon, so direct sunlight doesn't reach you
2. The upper atmosphere is still being lit by the sun (refracted light bouncing through atmospheric layers)
3. Blue light is preferentially scattered through the deep atmospheric path
4. Other colors are filtered out, leaving primarily blue
The result: a uniform blue sky color, deeper and more saturated than midday blue.
When it happens
Roughly:
- Evening blue hour: starts about 15 minutes after sunset, peaks around 25-30 minutes after sunset, ends around 40 minutes after sunset
- Morning blue hour: starts about 40 minutes before sunrise, peaks around 25-30 minutes before sunrise, ends about 15 minutes before sunrise
Duration varies with latitude:
- Tropical (low latitude): ~20-25 minutes
- Mid-latitude: ~25-35 minutes
- High latitude (above 50°): longer, especially in summer (an hour or more)
- Polar regions: blue hour can last hours during midnight sun periods
Why it's good for photography
Several reasons photographers love blue hour:
1. Even, soft light. No harsh shadows. Subjects are evenly lit by ambient sky.
2. Long exposures work. The dim conditions allow for long shutter speeds without overexposure. Light trails from cars, motion blur, and creative effects become possible.
3. Sky color contrast. The deep blue sky contrasts with warm tungsten city lights, creating visually dynamic scenes.
4. Dramatic mood. Cities at blue hour look vaguely surreal — the deep blue sky feels different from midday or full night.
5. Wedding and portrait work. Some photographers specifically schedule sessions for blue hour to create distinctive looks.
Common subjects
What photographers shoot during blue hour:
- City skylines: with lights starting to compete with the sky
- Street photography: shop windows, cafes, urban scenes
- Architecture: building lights against deep blue background
- Bridges: famously dramatic
- Long exposures of moving water (lakes, rivers) — silky water effects
- Long exposures of clouds — streaking, ethereal sky textures
- Astronomical photography isn't yet practical (sky too bright); dedicated astronomy photographers wait for full astronomical twilight
The transition from golden to blue hour
Golden hour (warm light period, sun 6° above to 6° below horizon) flows into blue hour seamlessly:
1. Golden hour begins ~30-40 minutes before sunset. Warm, low-angle light. Long shadows.
2. Sunset itself: dramatic colors at the horizon.
3. Civil twilight begins: sun crosses horizon. The sky is still warm/red.
4. Blue hour begins ~10-20 minutes after sunset. Sky deepens to blue.
5. Blue hour peaks around 25-30 minutes after sunset.
6. Blue hour ends when full darkness approaches.
For photographers, blue hour and the late phase of golden hour together provide ~1.5 hours of shootable conditions. After that, full astronomical darkness is for star photography.
Specific blue hour photography tips
Equipment:
- Tripod (long exposures require stability)
- Wide-angle or standard lens
- Manual or aperture-priority mode (camera meters can confuse in mixed light)
- Cable release or 2-second timer (avoid camera shake from button press)
Settings:
- Aperture f/8-f/11 for sharp landscape work
- ISO 100-400 for clean images
- Shutter 1-30 seconds depending on scene
- White balance: tungsten or daylight depending on what you want; both work
- Manual focus (autofocus can hunt in low light)
Timing:
- Arrive 30 minutes before sunset to set up
- Shoot golden hour first (sun above horizon)
- Continue through sunset
- Continue into civil twilight
- Peak blue hour starts ~25 minutes after sunset
- End ~40 minutes after sunset
Composition:
- Include city lights, street lamps, or windows for contrast
- Consider reflections in water if available
- Position to capture the deepest part of blue (typically east during western evening blue hour)
Famous blue hour photographs
A few iconic shots:
- Eiffel Tower during blue hour with light trails on the Champ de Mars
- Big Ben and Westminster Bridge at blue hour
- Manhattan skyline from Brooklyn during blue hour
- Tokyo Tower with surrounding city lights
- Sydney Opera House with lit sails
These compositions all rely on the deep-blue-sky-against-warm-lights pattern.
Mobile photography during blue hour
Modern smartphones can capture blue hour, but there are limitations:
- Auto-exposure may overexpose, washing out blue
- Use Pro mode if available (manual ISO and shutter)
- Use a small tripod for longer exposures
- Apple iPhone Night Mode handles blue hour better than older modes
Photo apps like Halide, ProCam, and others give more manual control on iOS. Pro Mode on Android phones offers similar control.
Difference from "magic hour"
Some photographers use "magic hour" interchangeably with golden hour, but technically:
- Golden hour: warm light period, sun above horizon to 6° below
- Blue hour: cool blue period, sun 4-8° below horizon
- Magic hour: sometimes used to mean "either golden or blue hour" generically
For precision in conversation, prefer "golden" and "blue" specifically.
When blue hour is best
- Sunset side: usually has more vibrant blue. The atmosphere is still recovering from heat of the day.
- Sunrise side: typically cooler and clearer. Atmosphere has settled overnight. The blue can be even more saturated but the window is shorter (people are usually less active before sunrise).
Geographic considerations
Some places have notably good blue hour conditions:
Coastal cities: often have stunning blue hour because of sea horizons and natural water features. Cinque Terre, Santorini, Sydney.
High elevation cities: clearer atmosphere makes blue more saturated. Cusco, Quito, Aspen.
Cities with major architecture: Paris, Rome, Istanbul, Hong Kong all have iconic skyline shots during blue hour.
Locations with active light pollution: surprisingly, can be photogenic during blue hour. The competition between sky-blue and city-lights creates compelling images.
FAQ
How is blue hour different from twilight?
Blue hour is approximately the same time as nautical twilight (sun -6° to -12° below horizon) but the term emphasizes the photographic and aesthetic aspect rather than the navigational meaning.
Can I plan a shoot for next week's blue hour?
Yes. Blue hour times are predictable. Use a tool like the sunrise-sunset page for your city — calculate the time about 25-30 minutes after sunset for peak blue hour.
Why doesn't blue hour happen on cloudy nights?
Cloud cover scatters light differently. On cloudy nights, the sky may stay gray rather than turning blue. Partial clouds can actually be photogenic — sometimes more dramatic than clear skies.
Is blue hour the same in every city?
The duration is similar (roughly 25-40 minutes at temperate latitudes). The exact appearance depends on atmospheric conditions, light pollution, and atmospheric clarity.
What time of day should I shoot for the deepest blue?
Peak deepest blue is typically 25-30 minutes after sunset. Shooting before this gives a lighter blue with more red/orange in the sky; shooting after gives a darker, more navy blue with more visible stars.
Can I shoot blue hour with my phone?
Yes, especially newer iPhones (iPhone 11+) and Galaxy phones with Night Mode. Use a tripod for best results. Pro mode (manual settings) on Android gives the most control.
Bottom line
Blue hour is the brief window 25-40 minutes after sunset (or before sunrise) when the sky turns a deep saturated blue. It's a favorite of photographers for its even light and dramatic mood. Plan around the sunrise-sunset page for any city to find your blue hour times.
For exact sunrise and sunset times that anchor blue hour calculations, the sunrise-sunset page is the tool.