As you know, but let me say about the "season word" of haiku.
The season word is not necessarily to be word "spring", or "summer"----. It's good everybody feels the season to the word as their commonsense, or as feelings of consensus of a cultural area. For example, in America, it is Independence Day, or Major League Baseball(MLB) in July. Like this, a national holiday, an annual event, an entrance ceremony, the commencement day, etc.,----of course only word "swimming" or "skiing" , or name of flower in the season, and also word "a season wind", I think they are OK.
In Japan, for hundreds years a large number of these season words have been amassed for making Haiku and Tanka(short poem in 31 letters) as the book called "Saijiki".
And season words have changed as times. Because life style has changed. There are many words which young people don't know in Saijiki. But those words have almost not deleted from Saijiki. I am interesting that obsolete season words are still alive in Saijiki.
I suggest you to make note of season word in America(or other country). Taking the note is the easiest way to make a Haiku.