Rowlands Castle Circular Walk

West Sussex hourly weather (Open Meteo)

Sunset: 15:57. Dusk: 16:37. Dark: 17:20. Moon 59% (22:59 to dawn)

Updated: Sat, 21-Dec at 11:36

Percentages are the chance of rain.

Weather data by Open-Meteo

West Sussex hourly weather (Met Office)

Sunset: 15:57. Dusk: 16:37. Dark: 17:20. Moon 59% (22:59 to dawn)

Updated: Sat, 21-Dec at 11:00

Percentages are the chance of rain.

Weather data by Met Office

Regional weather (Met Office)

Sunset: 15:57. Dusk: 16:37. Dark: 17:20. Moon 59% (22:59 to dawn)

Updated: Sat, 21-Dec at 11:38

South East England

Increasingly breezy. Some outbreaks of rain, clearing through the afternoon.

• Outbreaks of rain will clear southwards to some sunshine to end the afternoon
• Increasing chance of showers following in the evening to western parts
• Turning quite windy and feeling colder later
• Maximum Temperature 13C

Tonight:

• A windy night with some blustery showers, quickly passing through
• Some clear spells and probably remaining mostly dry towards London and Kent
• Minimum Temperature 2C

Sunday:

• Sunshine and a few blustery showers on Sunday - possibly wintry at first
• Windy and feeling cold
• Winds decreasing overnight
• Maximum Temperature 7C

Outlook for Monday to Wednesday:

• Monday starting fine and increasingly cloudy
• Some rain later and overnight
• Christmas Eve much milder with drizzle likely
• Christmas Day probably drier and remaining cloudy and feeling noticeably mild

UK Day 6-7 and week 2

• Christmas Day weather will be characterised by mild, cloudy conditions for most, with bits of drizzle in places and perhaps some more persistent rain in northwest Scotland
• This sets the scene for the next few days too, with an area of high pressure becoming established across much of the UK, probably centred over or just to the south of England
• The highest chance of rain and strong winds will be in northwest Scotland, with many other areas predominantly dry but rather cloudy, although more settled conditions may well extend to the northwest at times too
• Widely mild at first, perhaps exceptionally so in some places early on, but temperatures probably returning to nearer normal by early January
• Throughout, any clearer spells overnight may lead to localised frost and fog

UK Week 3 and 4

• Slowly-evolving weather expected through much of this period
• Overall, there is a reduced chance compared with normal of wet and windy spells, with instead greater potential for colder episodes during the first half of January
• While drier than average conditions are likely for many areas, some precipitation is still expected, which could lead to wintry hazards at times
• Temperatures are likely to be close to or a little above normal overall, but this could be made up of a mix of milder and colder interludes

Weather data by Met Office

West Sussex Air Quality (Pollen and UV)

Updated: Sat, 21-Dec at 11:36

Key : Low Medium High Very High

Pollens

These pollens are shown (in season):

• Grass
• Alder and birch (trees)
• Mugwort and Ragweed (weeds)

When out walking, wraparound glasses, a disposable or washable facemask, and being at the front of the group, all help.

Other forecasts: Met Office, University of Worcester

UV and Air Quality

The UV forecast takes account of cloud cover.

"Air Q", the European Air Quality index, is a mix of dust/particulates, ozone, sulphur and nitrous oxides

Data

Weather data by Open-Meteo and CAMS ENSEMBLE

West Sussex Visibility

Updated: Sat, 21-Dec at 11:36

Visibility in km. Above 50km is 'good'. Humidity and air pollution make it worse. Theoretical maximum is 300km/200 miles in clean dry polar air.

On the South Downs, at ~ 170m/500ft, the horizon is is ~ 45km/30 miles away. On a mountain at 1,000m/3,000ft, it is ~ 160km/100 miles away. Formula: horizon in km = √ (13 x altitude in m)

Weather data by Open-Meteo

West Sussex daylight

Notes

• Max Height (solar noon) is when the sun is highest in the sky.
• Day length is dawn to dusk as there is enough light for walking for at least 30 minutes before sunrise and after sunset, even on an overcast day.
• At 'Light' (nautical dawn) the horizon becomes visible. At 'Dawn' (civil dawn) there is enough light to read, and drivers can switch their lights off. Finally the sun rises.
• After sunset, there is still enough light to read until 'Dusk' (civil dusk) or lighting up time for drivers. The horizon is still visible until 'Dark' (nautical dusk).
• Times will vary if there is a hill on the horizon.

West Sussex moonlight

Moonlight chart for walking at night.

Notes

• The percentage of the moon which is illuminated doesn't vary much with location.
• A full moon is not just bigger, it is much brighter. A quarter moon (1/2 disk visible) give less than 5% of the illumination of a full moon. You can walk with a quarter moon if its high in the sky (after dusk for a growing moon, before dawn for a shrinking moon).
• Sky glow (light reflected by air or clouds) from nearby cities, and especially snow on the ground also effect light levels.
• Times will vary a few minutes, as (i) these figures are for the centre of the county the walk is in, (ii) if there are hills on the horizon, and (iii) if you are on a hill
• Sunlight is ~ 1,000,000 times brighter than moonlight.
• Of course, you need a cloudless night as well!

West Sussex weather (Accuweather)