July 21, 2026 · Castlereagh, Northern Ireland
Sunset in Castlereagh today is at 21:45. Day length is 16h 28m. See below for sunrise, solar noon, dawn and dusk — all times calculated astronomically for Castlereagh's coordinates and updated daily.
Castlereagh lies at 55°N. At this latitude, day length varies significantly through the year — from roughly 7–8 hours in midwinter to 16–17 hours at midsummer.
Sunset shifts later through spring and earlier through autumn — changing fastest near the equinoxes and slowest near the summer and winter solstices. See the year chart to visualise how sunset times shift month by month for Castlereagh.
The longest day in Castlereagh is around 17h 16m (around June 21). The shortest is around 7h 15m (around December 21). Days are currently getting shorter — losing about 3 minutes per day.
| Month | Sunset | Sunrise | Day length |
|---|---|---|---|
| January | 16:27 | 08:39 | 7h 48m |
| February | 17:29 | 07:49 | 9h 40m |
| March | 18:25 | 06:42 | 11h 42m |
| April | 20:24 | 06:25 | 13h 59m |
| May | 21:21 | 05:21 | 15h 60m |
| June | 22:01 | 04:48 | 17h 13m |
| July | 21:54 | 05:06 | 16h 47m |
| August | 21:00 | 05:58 | 15h 2m |
| September | 19:45 | 06:55 | 12h 51m |
| October | 18:30 | 07:50 | 10h 40m |
| November | 16:26 | 07:52 | 8h 34m |
| December | 15:59 | 08:39 | 7h 19m |