Each disease pathogen has a specific temperature range for growth and activity. Many powdery mildew diseases are late summer, warmer temperature diseases. Temperature affects how rapidly pathogens multiply. Soil temperature can also be critical for disease infection. Cool, wet soils promote fungal root diseases.
Temperature extremes can cause stress in host plants, increasing susceptibility.
The combination of wind and sun affects how quickly plant surfaces dry. Faster drying generally reduces the opportunity for infection. Wind can spread pathogens from one area to another, even many miles. Wind and rain together can be a deadly combination. Windblown rain can spread spores from infected plant tissue, blowing these pathogens to new host plants.