Contrary to popular convention, it is not the wonderful in an event that determines its "miraculousness" but the value and significance that that event holds for us.
A given occurrence can be most wondrous and still not be considered a miracle, but merely a natural "curiosity."
The fact that somewhere out there in a barren wilderness, a stone has rolled to the foot of a mountain, remaining upright all the while, is strange and astonishing, a wonder in itself.
In the absence of significance, however, it is not a miracle.
On the other hand, a perfectly natural occurrence can, under certain circumstances, be considered a miracle because of its significance to the human condition.
–Rabbi Adin Steinsaltz
From The Strife of the Spirit, p. 32, by Rabbi Adin Steinsaltz