Why bacterial food poisoning peak in summer？

[charlesxkinetic]

Up to now, I have two ideas.

1. Hot and wet climate favors bacterial growth.
2. Human activities - People go outdoor and eat ready-to-eat food. Improper storage of food during the trip favors bacterial growth.

Are there any more factors and reasons leading to an increased number of food poisoning cases in summer? Thanks!

[biohazard]

I'd say those are by far the two most important factors, unless I managed to forget something obvious. Actually, I cannot come up with any additional (good) reasons why there are more food poisoning in summer.

Theoretically, there could be some disease spreading animals that are more numerous during the summer (such as flies that may spread bacteria when they hopple on your coleslaw), but I'm pretty certain these type of factors contribute to just a fraction of total disease cases.

[mcar]

I think you have already summarized the important factors why there are increased spoilage during summer and of course, heat really increases the deterioration in the quality of the food as well.