September rain falls on the house. (1)
Any mention of the name of a month locates the poem in time. We know it's fall, and that comes with all sorts of baggage: bad weather, dying plants, changing leaves, and all that jazz.
In the failing light, the old grandmother (2)
The failing light reminds us that it's the time of year where daylight is shorter, but it does some symbolic work, too. We mean, who doesn't feel gloomy inside when it's so gloomy outside?
were both foretold by the almanac, (9)
The almanac suggests things that happened in the past, but "foretold" is a way of predicting something that is going to happen. Total time mash here, right? In fact, though time may be passing in this poem, we can't help but think that these characters are stuck, without any ability to move forward. Which makes sense—if their future is foretold, what's the point in bothering about it?