import os
import rasterio

file_path = os.path.abspath('path/to/tza10povcons125.tif')
raster = rasterio.open(file_path)
band = raster.read(1)

array([[ -3.39999995e+38,  -3.39999995e+38,  -3.39999995e+38, ...,
         -3.39999995e+38,  -3.39999995e+38,  -3.39999995e+38],
       [ -3.39999995e+38,  -3.39999995e+38,  -3.39999995e+38, ...,
         -3.39999995e+38,  -3.39999995e+38,  -3.39999995e+38],
       [ -3.39999995e+38,  -3.39999995e+38,  -3.39999995e+38, ...,
         -3.39999995e+38,  -3.39999995e+38,  -3.39999995e+38],
       ...,
       [ -3.39999995e+38,  -3.39999995e+38,  -3.39999995e+38, ...,
         -3.39999995e+38,  -3.39999995e+38,  -3.39999995e+38],
       [ -3.39999995e+38,  -3.39999995e+38,  -3.39999995e+38, ...,
         -3.39999995e+38,  -3.39999995e+38,  -3.39999995e+38],
       [ -3.39999995e+38,  -3.39999995e+38,  -3.39999995e+38, ...,
         -3.39999995e+38,  -3.39999995e+38,  -3.39999995e+38]], dtype=float32)

>>> import numpy as np
>>> np.finfo('float32').min
-3.4028235e+38