Kapha accumulates in late winter and breaks out in spring. The same structure runs a second time in the year, and this is the accumulation half of it.
Summer's heat is drying. It takes moisture out of the body steadily and invisibly, and dryness is Vata's defining quality. So through Grishma, Vata quietly accumulates — in the colon, in the joints, in the nervous system — while nothing at all appears to be wrong. When the rains arrive with cold, damp and a sudden drop in digestive strength, that accumulation aggravates, and the result is the classical monsoon picture: joint pain, bloating and gas, anxiety, disturbed sleep, irregular digestion, aches that seem to come from nowhere.
If you have ever noticed that your joints reliably complain when the weather breaks, this is the tradition's account of why.
The useful part is that accumulation is much cheaper to address than aggravation. Three weeks of unglamorous attention now is worth considerably more than treatment in August.
What that looks like: keep the oil up, internally and externally, even in the heat — a light oil like coconut in the evening rather than heavy sesame at midday. Do not let the summer's lighter eating become erratic eating; Vata responds to irregularity faster than to any single food. Salt is restricted this season, but not eliminated — sweating without replacing minerals is directly Vata-provoking. Keep water intake genuinely high. And protect sleep, which the short nights are already eroding.