Scilly, where it's located

The climate of Scilly is oceanic, with quite mild, rainy winters and mild, relatively rainy summers.
The islands are located south-west of the south-western tip of Great Britain, and have a particularly mild winter, and a climate that is not too rainy.
The average temperature of the coldest month (February) is of 7.9 °C (46 °F), that of the warmest month (August) is of 16.9 °C (62 °F). The lowest record is -7.2 °C (19.0 °F), the highest is 27.8 °C (82 °F). Here are the average temperatures.
Scilly - Average temperatures
Min (°C)66779121414131187
Max (°C)101011121417192018151210
Min (°F)434345454854575755524645
Max (°F)505052545763666864595450

Precipitation amounts to 865 millimeters (34.1 inches) per year: so, it is at an intermediate level. It ranges from 50 mm (2 in) in the driest months (May, June) to 100 mm (3.9 in) in the wettest (December). Here is the average precipitation.
Scilly - Average precipitation

On average, there are around 1,690 sunshine hours per year. Here are the average sunshine hours per day.
Scilly - Sunshine

The sea temperature ranges between 10 °C (50 °F) and 17 °C (63 °F). So, it never becomes warm for swimming. Here are the average sea temperatures.
Scilly - Sea temperature
Temp (°C)111010111214161717151312
Temp (°F)525050525457616363595554


Best Time

The best time to visit Scilly is the summer, or more generally from mid-May to mid-September: temperatures are generally good for outdoors activities, although it's better to bring an umbrella, and a sweatshirt or sweater for the evening or for cool days.