Teresina is located on the east side of the Parnaíba River at the border with
Maranhão state, at an altitude of about 72 meters. The city faces the city of Timon across the river and is situated between the Parnaíba River and its tributary the Poti River. The two rivers join at the city's northern end, where there is an environmental park with gazebos. Teresina is the largest capital in the northeastern territorial extension, at 1,756 km2. Located in a transition zone between the northeast and the Amazon (Mid-North), Teresina is surrounded by mata dos cocais, savannas and cerradões where many carnaúba, babaçu, buriti palms, jatobás, ipês, and many other medium-sized trees can be seen. In the region there are also remnants of Teresina Atlantic Forest, which makes the landscape shrub coverage very rich and dense.
Climate Teresina has a
tropical wet and dry climate (
Köppen climate classification:
Aw) with semi-humid characteristics and two seasons: the rainy season (which occurs in summer and autumn of the
Southern Hemisphere) and the dry season (which occurs in winter and spring). From January to May, due to the rains, the weather is hot and wet (likely to occur when there is fog in the morning), while from June to August the climate gets dry with relatively milder nights; in September to December the weather becomes hotter and humid decreases, with the gradual return of rainy conditions from October. This period is referred to as "Bro" by locals as the hottest months end with -bro in Portuguese: '
, ', '
, and '. A peculiar feature of the rains in the city are their speed and intensity, with strong winds, large force of water and very common lightning. The annual rainfall stands at around . The highest recorded daily precipitation was . Hot most of the year, Teresina has an average temperature around , with a minimum of in July and a maximum of in October. The lowest ever recorded in Teresina was in June, while the record hot temperature exceeds (October and November). Annually, there are approximately 129.4 days in which the maximum daily temperature reaches or exeeds . These fluctuations are mitigated by the contribution of the winds. Air quality is considered good in Teresina, except in the driest period, when the relative humidity drops, and there are occurrences of fires. ==Demographics==