We’re a bit late on this one, but it’s appropriate because recent weather has had me wishing it were still cool and spring-like.
(Atsusa samusa mo higan made; “Heat and cold until the equinox”)
Summer heat potentially lasts until the autumnal equinox, but not after. Winter cold potentially lasts until the vernal equinox, but not after. By the time of the equinox, a season’s extreme temperatures have calmed down to a happy medium.
暑さ (atsusa) is the nominal (noun) form of the adjective 暑い (atsui), “hot.” Similarly, 寒さ (samusa) is the nominal form of 寒い (samui), “cold.” They are connected with the conjunctive particle も (mo), “and” or “also.” Another も after 暑さ would be acceptable and appropriate, but for compactness’ sake is not used here.
This noun phrase is followed by the noun 彼岸 (higan). While I translated this above as “equinox,” it seems that the term actually refers to an “equinoctial week,” i.e. a span of time surrounding the equinox rather than a single day. まで (made, pronounced like “ma day”) is a particle implying the end of a motion: “to” or “until.”
Higan is a Buddhist term, translated from the Sanskrit “param.” The characters literally mean “that shore (of a river),” and contrast with 此岸 (shigan), “this shore.” Metaphorically “this shore” is this material world, while “that shore” is the world of enlightenment. It appears that the term came to be applied to the equinoxes because their weather is neither too hot nor too cold, and this was metaphorically likened to the balanced, pleasant state of existence one reaches in Nirvana.
(“Sangatsu joujun na no ni, mou sanjuudo chikaku? Atsusa samusa mo higan made tte iu na nai!” “Ha ha ha, chikyuuondanka kamo.”)
[“It’s only early March, and temperatures are already close to 30°?* Don’t they say heat and cold last until the equinox?!” “Ha ha ha, it’s probably global warming.”]
*(C, or 86°F)