All the fireworks set off on or about the 4th of July (in the US, of course) should produce a plethora of nucleation particles for water vapor. So does this actually cause the weather on or just after that date to be especially rainy? Has anyone done a study on it, say comparing the amount of precip on those days with those of other summer days?
We’ve been having a very serious drought in these parts. Last night it began raining and we’ve had showers on and off ever since. How can we get a grant to study this possible advantage of using fireworks. I’ll write the National Fireworks Manufactureres Assoc. and see if they’ll chip in. 
One time on a trip back to Iowa we got snowed on in Jackson Hole, WY on the 4th of July.