On Sao Miguel you have many little narrow roads that are very charming, but they can also be a little dangrous if you are transporting yourself by foot or bicycle.
There is often little or no pavement, both in the towns and on the roads connecting the towns.
The good news is that they have started creating walking and cycling paths around the island too, but you still need to be careful in the places where they have no paths and where the road is narrow.
It is true that the climate in Azores is not very stable. The region has a temperated climate where temperatures range from 14 to 20 degrees celsius most of the year along with high levels of relative humidity, which make the climate very warm.
Since the islands are located in the middle of the Atlantic it is very common that the sea sometimes rises to dangerous levels, especially for small boats, usually during winter.
The region is also affected by numerous earthquakes, however, most of them only are detected by special equipment and make no harm to buildings or people. I haven't heard of any big earthquake on the last 20 years...
When visiting the higher places, and even if there is a clear sky at the city, to find fog formation which can "destroy" the visitors plans to see the lagoons or other sights.
Sometimes it's stormy and then the torrential rains can cause landslides. Please keep this in mind if hiking in the hills. You should also remember that the water level in rivers can rise dramatically during and after a heavy rainfall.
Don't leave anything in plain view while parked ,especially in the more remote parking areas as theft from cars seem to be the only noticeable crime on this entire island. Otherwise, this island is safe just about anywhere at any time, always using common sense.
If you're going to bathe in ferrous water (Poça Dona Beija, Parque Terra Nostra, Caldeira Velha, for example), don't forget to bring a dark bikini/swimming suit/whatever, or alternatively an old one that you don't care about anymore. The ferrous water leaves orange stains on the fabric that are almost impossible to get rid of.
If you already stained your swimming suit, try squeezing a lemon over the stain, powder it with salt and leave it in direct sun exposure. Then perform regular washing. It's not 100% effective though.
It's normal to see cows everywhere around the island. On the slopes, on the plaines or on the road! Careful is needed when driving through the island