Isles of Scilly Weather & Travel Guide
What to expect, how to plan, and what to do if services are disrupted.
Photo: Hugh Town harbour, St Mary's (26 August 2006) — Chris Gorringe · CC BY-SA 2.0. Display may be cropped. Photo details.
Independent guide — not affiliated with any operator. All prices, times and policies are indicative. Verify with operators before booking. Editorial Policy · Research · Disclaimer
Weather and Travel Disruption
All three transport services to the Isles of Scilly — the Scillonian III ferry, Skybus flights, and the Penzance Helicopter — can be affected by weather. The crossing sits in the open Atlantic, and all operators prioritise passenger safety above schedules. Disruptions are relatively rare in summer but do occur, and it is important to plan accordingly.
Scillonian III Ferry
Primary risk: Rough seas & high winds
The ferry crosses approximately 28 miles of open Atlantic water. It may be cancelled or delayed when significant wave heights or wind speeds exceed safe operating thresholds. Spring and autumn crossings are more likely to be affected. If you are prone to seasickness, check the forecast before travelling and consider taking appropriate medication.
Skybus Flights
Primary risk: Fog & low cloud
Fog, low cloud and strong winds can delay or cancel flights when operating limits are not met. Conditions at both departure and destination matter. Check the operator's current advice rather than assuming fog will clear by a particular time.
Penzance Helicopter
Primary risk: Strong winds & reduced visibility
The helicopter is not affected by sea conditions, making it more resilient than the ferry in Atlantic swells. However, strong winds (particularly on the Tresco helipad, which is more exposed) and reduced visibility can still cause cancellations or delays.
How to Plan for Disruption
- Always buy comprehensive travel insurance that covers transport cancellation and accommodation costs.
- Build flexibility into your plans — avoid booking non-refundable accommodation for your very first night if you're arriving on a tight schedule.
- Check the weather forecast and operator service status the day before and on the morning of travel.
- Keep the operator's customer service number saved — Isles of Scilly Travel: 01720 424220; Penzance Helicopters: 01736 780828.
- If the ferry is cancelled, ask about Skybus availability — operators sometimes transfer passengers between services.
- Consider arriving the night before and staying in Penzance or West Cornwall to reduce weather risk on the day.
Climate on the Isles of Scilly
The Isles of Scilly have a mild maritime climate. Met Office 1991–2020 averages for St Mary's put January daytime highs near 10°C and overnight lows near 6°C; July and August daytime highs average around 19–20°C. Frost is uncommon, but it does occur. These are long-term averages, not a forecast.
The best weather months are typically May to September. July and August are the warmest and sunniest. Spring (April–May) offers wildflower season and fewer crowds. October can be spectacular for birdwatchers. Winter visits are very quiet but accommodation and services are more limited.
Source: Met Office St Mary’s climate averages · Checked 9 September 2026.
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Weather & Disruption — FAQs
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