Research is pretty clear on what causes a fb outbreak. It's mostly about the weather. Temperature but mostly water; rain, humidity, and dew. It is ever present but cankers that ooze in spring are especially bad.
Hail and insect punctures can be a factor but mostly on tender young foliage. However we have lots of hail and cicada in west Texas and I've only seen fb once in Alpine, the one yr we had a rainy wet spring. The cicada in Amarillo are every yr all summer. Their whining racket is enough to drive a guy crazy. They puncture the limbs every summer but zero fb.
There are models that predict fb based on weather. I think they even have sensors that detect water on the foliage.
It is highly variable and outbreaks can seemingly come out of no where. So I don't discount anyone's experience.
I was blown away the one yr it hit hard here after not seeing it in 45 yrs.
Here's a quote from my link:
Fire blight bacteria overwinter in cankers on twigs, branches, or trunks of host trees. In spring when the weather is sufficiently warm and moist and trees resume growth, a small percentage of the cankers become active as bacteria multiply and ooze from branch or twig surfaces in a light tan liquid. Splashing rain or insects transmit the bacteria to nearby blossoms or succulent growing shoots. Once blossoms are contaminated with the bacteria, honey bees become efficient carriers of the pathogen.
Injuries on tender young leaves and shoots, caused by wind, hail, or insect punctures, are easily invaded by the fire blight bacteria. Such infections lead to shoot blight. Ideal conditions for infection, disease development, and spread of the pathogen are rainy or humid weather with daytime temperatures from 75° to 85°F, especially when night temperatures stay above 55°F.
Fire blight bacteria generally don’t move uniformly through the bark but invade healthy wood by moving in narrow paths up to 1 1⁄2 inches wide in the outer bark ahead of the main infection. These long, narrow infections can extend 2 to 3 feet beyond the edge of the main infection or canker. If you expose bark from an infected woody area, you will see that the diseased tissue closest to the main canker is brown. Farther out, the infection turns red and then appears as flecking. Just beyond the visible infection the tissue will look healthy.
Tree vigor has a major influence on the extent of fire blight damage. Once established, the distance the pathogen moves relates directly to the susceptibility of the tree and rate of tree growth. Vigorously growing shoots are the most severely affected; therefore, conditions such as high soil fertility and abundant soil moisture, which favor rapid shoot growth, increase the severity of damage to trees. In general, trees are more susceptible when young and suffer less damage as they age.
Fire blight development is influenced primarily by seasonal weather. When temperatures of 75° to 85°F are accompanied by intermittent rain or hail, conditions are ideal for disease development. The succulent tissue of rapidly growing trees is especially vulnerable; thus excess nitrogen fertilization and heavy pruning, which promote such growth, should be avoided. Trees shouldn’t be irrigated during bloom. Monitor trees regularly, and remove and destroy fire blight infections. (See Removing Diseased Wood.) If fire blight has been a problem in the past, apply blossom sprays. Sprays prevent new infections but won’t eliminate wood infections; these must be pruned out. In years when weather conditions are very conducive to fire blight development, it can be difficult if not impossible to control the disease.