That's impressive. What are the "right conditions"?

Usablight.org monitors conditions in the states. I don't think they send reports on where blight might appear, but the site shows where cases of confirmed blight have occurred on a map. I find this helpful since so many people on forums like gardenweb think any disease symptoms they see are blight. If late blight hasn't been found in your state, it's unlikely that it's in your garden. Early blight is much more common, but it is an unrelated and less lethal problem.

When the temperature is over 10C and relative humidity is over 90% for the first 11 hours and last 11 hours over a 48 hour period, the phytopthera spores are able to germinate...so after the first period, we have a 24hour window to act pre-emptively rather than regular spraying whether needed or not.

We have all kinds of alerts. TOMCAST is one of the better blight forecast sites in the northeast US. Throughout the Mid- Atlantic region the extension service provides very good warning of Late Blight movement. They even keep track of strains since a major concern is avoiding mating strains.