Angra do Heroísmo, where it's located

The climate of Angra do Heroísmo is temperate oceanic, with mild, rainy winters and pleasantly warm summers.
The city is located on the southern coast of the island of Terceira. The highest peak on the island is the Serra de Santa Bárbara, an inactive volcano of 1,021 meters (3,356 feet), inside which there is a caldera, Lagoa Negra.
The average temperature of the coldest month (February) is of 13.8 °C (57 °F), that of the warmest month (August) is of 22.1 °C (72 °F). The lowest record (of the 1971/2000 period) is 3.7 °C (39 °F), the highest is 29.2 °C (85 °F). Here are the average temperatures.
Angra do Heroísmo - Average temperatures
Min (°C)121212121416181918161413
Max (°C)161616171921242524211917
Min (°F)545454545761646664615755
Max (°F)616161636670757775706663

Precipitation amounts to 1,085 millimeters (42.7 inches) per year: so, it is at an intermediate level. It ranges from 35 mm (1.4 in) in the driest month (July) to 135 mm (5.3 in) in the wettest (December). Here is the average precipitation.
Angra do Heroísmo - Average precipitation

On average, there are around 1,960 sunshine hours per year. Here are the average sunshine hours per day.
Angra do Heroísmo - Sunshine

The sea temperature ranges between 16 °C (61 °F) and 23 °C (73 °F). The sea is never very warm, though it is warm enough for swimming from July to September. Here are the average sea temperatures.
Angra do Heroísmo - Sea temperature
Temp (°C)161616161719222323211917
Temp (°F)616161616366727373706663

Angra do Heroísmo

Best Time

The best time to visit Angra do Heroísmo runs from June to August, since it is the warmest and the least rainy period of the year. In May, you can go, but cool and rainy days are more frequent.
Even in summer, it's better to bring a sweatshirt, and maybe a light jacket for the evening.