Here I will recommend sweet whites - you can pick Sticky Chardonnay or Weingut Fritz Windisch Dornfelder. A tiny dazzle of sweetness across palate that dilute the dark side of the rain.
Stick Chardonnay from D'arenberg -
One of D'arenbergs' simplest style wine, picking late harvest chardonnay. The kumquat and marmalade character gives a citric stimulation to our taste buds, just like rain is an incitement to a heat wave in summer. Its golden yellow color often gives a glimpse to your grey mood. It did energizes me when I bought it at HKD$10!!! Also, if rain didn't last that long, you can often keep that in fridge until another rainy day. Such an amenity of late-harvest wines.
Weingut Fritz Windisch Heimersheimer Rotenfels Dornfelder QbA -
When you say, how come rain often goes with summer when summer supposes to be sunshine and sea, this is such a cynical thing. Then that's exactly what Dornfelder is - a red sweet still wine. Do not judge the mismatch. Without rain, you can't live in drought. Its floral cherry and plummy red wine softens the sadness of rain. This should be the most effective wine in Germany as this is the second most common red wine vines planted in Germany.
When it's raining next time, pour the glass, sat next to the window enjoy the raindrop hitting your window. We call this moment - Romance.