2026 Cybi Coastal Marathon - Aug 1 Countdown

Q: How long and hilly is the course?

It is a single loop of Holy Island run over the full marathon distance (26.2 miles / 42.195 km), with around +200 m of climbing. The route is mostly runnable coastal path, but the defining feature is a short, steep summit of Holyhead Mountain at about mile 22, followed by a technical descent and a couple more cliff-path miles to the finish.

Q: Is the Cybi Coastal Marathon a Boston qualifier?

No. Because the course is an uncertified trail route on the Anglesey Coastal Path rather than a certified road race, it is not BQ-eligible. Run it for the scenery and the challenge, not for a qualifying time.

Q: What shoes and kit should I wear?

Trail shoes are strongly recommended. The route mixes paved path, single-track, fields, sandy beach and short road sections, and can be very muddy after rain. With an exposed clifftop on the Welsh coast, pack a light windproof layer and plan to carry some of your own fluid — aid stations are spread out and runners are asked to bring their own cup or bottle to refill.

Q: What scenery does the route pass?

The loop circles Holy Island past Silver Bay, Rhoscolyn and Trearddur Bay, along dramatic sea cliffs with views of the South Stack lighthouse, before the final climb of Holyhead Mountain (Mynydd Twr). It is regularly called one of the most scenic — and most challenging — marathons in the UK.

Q: Who organises it and where does the money go?

It is a not-for-profit event run by local volunteers, with the HQ at the RNLI Holyhead lifeboat station on Newry Beach. Proceeds support the local RNLI lifeboat crews (Holyhead and Trearddur Bay), so your entry doubles as a donation to coastal rescue.

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Race Information

Race	2026 Cybi Coastal Marathon - Aug 1
City	Holyhead
Date	2026-08-01 at 09:00
Field Size	~234 runners
Time Limit	8 hours
Cutoff pace	11:23/km
Timezone	Europe/London
Official Site	Cybi Coastal Marathon (RNLI fundraiser)

Race Day Weather

Average Temperature	15.6°C / 60°F
Humidity	86%
Wind	28.7 km/h
Rain Chance	56%
Typical Conditions	Cool, breezy, often-overcast Anglesey coast morning with sea air

What to Prepare: Early August on Holy Island is mild but exposed — daytime highs near 64°F (18°C) with a steady ~20 km/h sea breeze and a roughly 30% rain chance. The clifftop singletrack gets very muddy after rain, so pack trail shoes and a light wind layer rather than racing in road kit.

Based on historical averages for race week. Use our Weather Score Calculator and What to Wear Guide for personalized advice.

Wind Impact on Race Day

Wind at 28.7 km/h can affect your marathon pace by 5-15 seconds per kilometer. Headwinds slow you down exponentially — a 20 km/h wind costs more than twice a 10 km/h wind.

Calculate your wind-adjusted pace →

Race-Week Climate

Based on 20 years of race-week weather (2005-2024), MERRA-2 reanalysis

	Cooler	Typical	Warmer
Temperature	14.4°C	15.6°C	16.8°C
Dew point	11.2°C	13.2°C	15.1°C

Wet-day chance: 56% Runnability: 66/100

Data: NASA POWER (MERRA-2 reanalysis), NASA Langley Research Center

Course Profile

Course Type	Loop (coastal trail)
Elevation Gain	200m
Terrain	Trail (coastal path, beach, single-track, short road sections)
Profile	A tough, scenic single-loop trail marathon that circumnavigates Holy Island (Ynys Cybi) on the Anglesey Coastal Path. The route sticks mostly to the waymarked coastal path with a few small diversions to bring it in at the full marathon distance (26.2 miles / 42.195 km), but it is not a certified road course, so it does not count as a Boston qualifier. Total climbing is around +200 m, with the signature sting being a short, steep summit of Holyhead Mountain near mile 22 followed by a technical descent and a pace-sapping run-in along the cliffs.

Prepare for 2026 Cybi Coastal Marathon - Aug 1

Use our free training tools to get race-ready:

Running Pace Calculator — Min/km, Finish Time & Pace Chart

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Free Pace Band Generator — Printable Race Day Wristband

Free printable pace band for marathon, half marathon, or custom distance. Choose even, negative, or ...

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Marathon Wake-Up Time Calculator — Race Morning Timeline

7 AM race, wake at 3:45 AM? Enter the gun time; we work backward through meal, gear, bathroom, warm-...

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Dew Point Running Calculator — Pace Adjustment Chart

Enter temperature and humidity to calculate dew point and its impact on your running pace. 7-zone ch...

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Wind Effect on Running — How Much Does Wind Slow You?

How much does a headwind actually slow you down? This free calculator turns wind speed and direction...

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Elevation Gain/Loss Impact Calculator

How much will hills slow you down? Enter elevation gain, loss, and distance to see adjusted pace, di...

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Frequently Asked Questions

How do you enter the Cybi Coastal Marathon?

Entry for the 2026 race has closed — registration ended on June 30, 2026, and this small community event has sold out with no sign of reopening before the August 1 race. Entry is first-come and online (no lottery), and in a typical year it opens around New Year (Dec 31 / Jan 1) through the official site at cybicoastalmarathon.com; the 2025 marathon fee was £45 (the separate Half Cybi 25K was £35). Use the .com address: the old .co.uk domain has been taken over by an unrelated site.

How long and hilly is the course?

It is a single loop of Holy Island run over the full marathon distance (26.2 miles / 42.195 km), with around +200 m of climbing. The route is mostly runnable coastal path, but the defining feature is a short, steep summit of Holyhead Mountain at about mile 22, followed by a technical descent and a couple more cliff-path miles to the finish.

Is the Cybi Coastal Marathon a Boston qualifier?

No. Because the course is an uncertified trail route on the Anglesey Coastal Path rather than a certified road race, it is not BQ-eligible. Run it for the scenery and the challenge, not for a qualifying time.

What shoes and kit should I wear?

Trail shoes are strongly recommended. The route mixes paved path, single-track, fields, sandy beach and short road sections, and can be very muddy after rain. With an exposed clifftop on the Welsh coast, pack a light windproof layer and plan to carry some of your own fluid — aid stations are spread out and runners are asked to bring their own cup or bottle to refill.

Is there a time limit?

This is a relaxed community trail event rather than a strict big-city race, so it suits a wide range of finishers; recent winners came home in about 3:22. An official cut-off is not clearly published, so plan for a generous limit (around 8 hours) and confirm the exact marshal cut-off with the organisers before race day if you expect to be near the back of the field.

What scenery does the route pass?

The loop circles Holy Island past Silver Bay, Rhoscolyn and Trearddur Bay, along dramatic sea cliffs with views of the South Stack lighthouse, before the final climb of Holyhead Mountain (Mynydd Twr). It is regularly called one of the most scenic — and most challenging — marathons in the UK.

Who organises it and where does the money go?

It is a not-for-profit event run by local volunteers, with the HQ at the RNLI Holyhead lifeboat station on Newry Beach. Proceeds support the local RNLI lifeboat crews (Holyhead and Trearddur Bay), so your entry doubles as a donation to coastal rescue.