A novel soybean variety, designated XR33A13 is provided. Also provided are the seeds of soybean variety XR33A13, cells from soybean variety XR33A13, plants of soybean XR33A13, and plant parts of soybean variety XR33A13. Methods provided include producing a soybean plant by crossing soybean variety XR33A13 with another soybean plant, methods for introgressing a transgenic trait, a mutant trait, and/or a native trait into soybean variety XR33A13, methods for producing other soybean varieties or plant parts derived from soybean variety XR33A13, and methods of characterizing soybean variety XR33A13. Soybean seed, cells, plants, germplasm, breeding lines, varieties, and plant parts produced by these methods and/or derived from soybean variety XR33A13 are further provided.