Soil health, micronutrients, and the flora of a healthy biome will be different from one garden to another, so you what you both are reporting probably reflects the soil in your area. It isn't just weather that makes a difference. From my organic gardening guru's page on Early blight: Control this disease by planting resistant cultivars and soaking seed in a disinfecting solution such as a hydrogen peroxide mixture before planting. Spray plants with compost tea, treat soil with cornmeal products.

The hydrogen peroxide is the 3% solution you buy in the grocery store, and it is a way to kill fungus. By soaking your seeds you are killing any spores that might come along. Cornmeal products are also good to kill fungal spores in the soil and on plants. If you make cornmeal tea - soak a cup of cornmeal in a few cups of water for a while then strain the solids and spray the liquid on plants where you want to prevent or slow blight. Here are more cornmeal uses.