Most people recommend a light weight rain jacket.
After many USA and foreign trips we alter the item slightly.
On-line or your local big-box store has a selection of inexpensive rain ponchos.
We want to stay dry in sprinkles or light rains, not prepare for a monsoon.
Such ponchos . . .
. . . ultra-cheap and as low as $0.75 each
. . . extremely thin material (2-3 mils)
. . . they tear easily so usually good for only one wearing
. . . easily disposed after use
. . . folded they are the size of a mail envelope
. . . several can be easily packed in luggage
. . . one-or-two in day pack take no space and only a few ounces