If you smell a foul odor near the Southport area of the city, this isn't unusual.

Every fall, an unpleasant odor forms particularly in the Bridgeway and Port areas, according to the West Sacramento City iLights blog.

The Sacramento Metro Air Quality Management District said the vegetation in the causeway and Yolo Bypass starts to deteriorate around this time and creates an odor. The algae and wetland vegetation sinks to the bottom of water bodies and decomposes, creating sulfur dioxide and other foul-smelling gases, according to City iLights.

This normally happens every year and due to proximity, West Sacramento gets hit with a stronger smell.

Warm days and cool nights cause a thermal current, bringing smells to the surface. During autumn, temperature inversions with little to no wind are common and this pattern traps the odors and intensifies the problem, according to City iLights.

At night, air becomes heavier as it cools and traps the odors being released from the organic matter. In the winter vegetation is dormant, while in the summer and spring vegetation is growing, which eliminates the issue of dead vegetation and odors.