Two people argue, gently, about sleeping outside on a balcony. One wants to do it; the other keeps raising objections. Rain might come, it's too cold, the neighbours will see. But the first voice answers each excuse by shrinking it. It won't rain fast, the poem has it say, and it won't be too much of a hurry. The cold isn't excessive or overbearing. The playful "dear" suggests affection rather than a real quarrel.
The last exchange is the best joke. When the objection is "There are neighbours," the reply is "We are the neighbours…" The balcony isn't overlooked by strangers at all, because the two of them are the ones who share this space. The trailing dots leave the thought hanging, as if the argument has simply run out of reasons.
The mood is light, teasing and intimate. The short lines make the talk sound quick and easy, and the persuader seems patient, a little cheeky, and sure of being understood.