Are there any yellow sack spiders in Windsor, Ontario?!

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I haven't seen any, especially in the snow. They are closer to London and Niagara in the fruit belt. I wouldn't fear them - worry about the traffic instead.

Univ of Windsor/guelph

Yellow sac spiders can be found all across the United States. Cheiracanthium mildei, like the hobo spider, came over to the United States from Europe around the 1940s. It is centralized around Seattle, Washington, but its range expands out across the Pacific Northwest and Southwestern Canada.

Yellow sac spiders are generally outdoor spiders, preferring foliage to structure, at least in warmer climates or seasons. But sac spiders are hunters, and they will search for prey indoors when there is little to be found outside. Thus, in the fall, they may move inside dwellings if they can find a food source therein.

According to Dr. Barb Ogg of the University of Nebraska, sac spiders are nocturnal hunters. "Indoors, they can be observed on walls and ceilings, but drop to the floor to seek cover when disturbed . . . Sac spiders construct a silken tube or sac in a protected area, such as within a leaf, under landscape timbers or logs, or at the junction of a wall and ceiling, and they use this sac as their daytime retreat. This is how the sac spider gets its name. These spiders do not build webs."