Rio Grande generally offers a reasonably safe environment. As with any place, it is important to stay aware of your surroundings at all times. There are areas in the city that may be less safe at night, so plan accordingly and use reputable transportation. As a solo female traveler, you should also be cautious about your belongings and avoid showing off expensive items. Knowledge of basic Portuguese can be helpful for communication and to avoid possible misunderstandings. All in all, with sensible precautions, your journey can be enjoyable and secure.