Greenwich Almanac


If you are planning your own adventure, here is some information you may find usefull.


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Greenwich, Greenwich Lat:51.4783 Lon:0.0083



Weather for Greenwich

Weather: overcast

Temperature: 12.8°c

Pressure: 1024.5 mb Δ-0.33 Steady

Humidity: 50%

Wind: 40° 6kts

Forecast: Fine weather ☼




Greenwich Sunclock for 06 May 2025


Litha Yule Ostara Mabon Imbolc Beltain Lammas Samhain Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Moon above Horizon Time (inside) Date (outside) Solar Time Waxing Gibbous Flower Moon 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Solar times

Sunrise: 05:22:35

Sunset: 20:31:34


Lunar times

Next full moon: 2025/5/12 16:55:53

Next new moon: 2025/5/27 03:02:17



The clock above shows the times and dates of astronomical events with reference to BST Today, times are shown inside the circle and dates outside the circle (one solar day and one year respectively).

It shows times of sunrise and sunset plus Dawn and Dusk, it also shows times of moonrise and moonset.


The blue sections of the face show times of three definitions of twilight, light blue is civil twilight where there should be enough light to conduct normal activities, mid blue shows nautical twilight where there is enough light to be able to see the horizon for navigation and dark blue shows astronomical twilight when it is not dark enough for astronomical observations.


The dates shown are for the current moon phase along with dates for the Equinox's, Solstice's and cross quarter days.


Greenwich Sidereal, Solar and Mean Time.


Siderial time or angle expressed in Hours, minues and seconds is a system whereby astronomers can locate celestial objects in the sky and is based on the time it takes the Earth to rotate to the same direction in space with reference to distant stars (as opposed to the Sun ) which is aproximatly 23 hrs 56 mins. Siderial time and Greenwich Mean time are aproximatly equal at the Autumn Equinox and siderial time will gain about 4 minutes each day throughout the year so each year there is one extra siderial 'day' compared to the number of solar days.


Greenwich Mean Time GMT, is the average (mean) solar time at the Greenwich Meridian 0° longitude. Until 1972 GMT was the International civil time standard, this has now been replaced with UTC (Universal Coordinated Time).


Local Mean Time is the average (mean) solar time for your local meridian, your longitude(0.0083°) will determine if you are ahead or behind your timezone by a factor of 4 minutes per degree, locations further West are behind.


Prior to the coming of the railways, most major towns adopted local mean time, which was dependant on their longitude so Penzance local time was 22mins later than Greenwich, this caused problems with the railway timetables, to solve the problem local clocks were set from the railway train guards watch so all of the UK started to use Standard time (GMT) also called 'railway time'.


Apparent Solar Time is based on the rotation of the earth and the position of the sun in the sky with respect to the local meridian. This is the time as shown on a sundial, and is represented on the clock above by the orange hand. This is the oldest method of timekeeping dating back over 5000 years to egyptian times.
Today in Greenwich apparent solar time is offset from BST by -56:26.


The difference between Apparent Solar Time and Local Mean Time can vary by as much as +- 16 minutes throughout the year, this is known as the Equation of time, and is due to the tilt in the earth's axis and eccentricity of the Earth's orbit around the Sun.
The length of a solar day, the time between two successive solar noons varies from 24h 30s in December to 23h 59m 39s in September.


Equation of time graph for Greenwich 0° Longitude.


Difference Value Date
Sundial behind -14 min 24 s 11 February
Same time 0 min 0 s 14 April
Sundial ahead +3 min 36 s 12 May
Same time 0 min 0 s 10 June
Sundial behind -6 min 24 s 24 July
Same time 0 min 0 s 28 August
Sundial ahead +16 min 30 s 29 October
Same time 0 min 0 s 22 December


For more information see: Equation of Time.


British Summer Time.

In the United Kingdom BST, one hour in advance of GMT, will be kept from 30 Mar 2025 to 26 Oct 2025.

Daylight Saving Time is just a way of fooling people into getting up an hour earlier during the summer months.


2025 Seasons.


2025 Festivals.

Cross Quarter Days


Christian Festivals


Saints Days


2025 Public Holidays


Other notable dates



All times are Local time for Greenwich (BST).


Please note: All of the information on this web site is generated by software i have developed and is for personal interest only.
Do not base any decisions on information contained within this page.
While i try to make all information as accurate as possible it may contain errors or omissions.


Weather data from open-meteo.com (CC BY 4.0)


Page generated on 06 May 2025 13:48
Version: 3.1