This is a poem basically giving us an inside scoop on people who are so used to living in storm weather and also an inside scoop of memories of the past. Explaining how the organization of the poem and the use of concrete details reveal its literal and its metaphorical meanings, the poem is in a chronological order already giving us a view into the poem.
The organization and the concrete details signify both the literal and the metaphorical meaning. In a literal sense, the order in which this person is getting to know that there's a storm coming give us a proper imagery with the concrete details. "Storm Warning" is obviously a person getting a warning for a storm. The poem tells us the process that is taken to prepare them, and to protect them from the storm with a wonder of how time can quickly change. In a metaphorical way, "Weather abroad and weather in the heart alike come on Regardless of prediction."
This line used in the second stanza hints us of something beyond a storm outside. This person is comparing a storm outside and a storm inside being the same thing even though they are both unpredictable. A concrete detail is given in the last line of the third stanza, "We can only close the shutters." The last stanza literally means that "now it's dark outside, let's close the curtain although the keyhole is still going to bring in wind. But oh well, people who live here know how to prepare best. Its metaphorical meaning goes deep. Something like "although I have shut all the doors from my past, there's still a portion of my heart that's there and can't forget (keyhole). But this is something I've learnt to do, cope with whatever is left."
In conclusion, the literal meaning of the entire poem is a basic warning for a storm. On the other hand, metaphorical meaning is a storm inside a heart, a storm of past. The organization and the concrete details help us figure out the hidden meaning in the poem, where the mood is pretty dull. "This is our sole defense against the season." The things mentioned in the poem are the basic everyday things these people do. They are used to be in the storm, both literally and metaphorically, but have learnt to cope with both.