El último verano.

El último verano.
 

El "Writing Couch" en Span¡shDictionary.com dice que:
El último verano. = "Last summer".
El último mes. = "The last month".
¿Si "el último verano" es "last summer" por qué "el último mes" no está "last month?.

Como siempre, gracias.

Last summer = El verano pasado
Last month = El mes pasado.

This is the last month I'm working. I'm retiring first day next month = Éste es el último mes que trabajo. El primer día del mes próximo me jubilo.

El último verano means either there won't be summers any more, or it is the last summer for someone in certain conditions

El último verano en el que fui feliz fue cuando salía con Rosita. = The last summer I was happy was the one I was dating Rosie.

Good question, Bob!
The opening interrogation mark directly precedes the interrogative.

Very helpful response!
You could omit 'the one', but 'when' needs to be in the English translation. It's possible to substitute 'in which' for 'when', but it sounds a bit stilted to me (a speaker of American English).

Thank you very much, Rusty!

Hearing so many people.leaving words or even parts of the speech out has inspired me to be ... kind of telegraphic.

You taught me something important: I thought about using "in which" there, but it sounds lofty to me too, as "en el cual" also does. Fortunately we have "en el que" an the highly colloquial "en que", but both bring me to "in which" again. I should have thought about using "when", but again, in this case "cuando" sounds stilted as stilted can be, kind of the Gettysburg address, not Lincoln's but the previous speaker's.

Gracias Rusty y Alec. Eso tiene sentido.

Último mes = Last and final.
El último mes de verano voy a la playa cada día.

El mes pasado = The previous month.
El mes pasado tenía trabaja cada día así que no pudo a la playa.

Poco por poco estoy aprendiendo.