When talking about past weather predictions, you often need to express what you hoped, doubted, or thought had already happened. To describe an action that happened before another past action in contexts that trigger the subjunctive, use the pluperfect subjunctive (trapassato congiuntivo).
The pluperfect subjunctive is a compound tense. You form it by combining the imperfect subjunctive of the helper verb (avere or essere) with the past participle of your main verb.
Here is a quick reminder of the imperfect subjunctive forms for the helper verbs:
| Pronoun | Avere | Essere |
|---|
| io | avessi | fossi |
| tu | avessi | fossi |
| lui/lei | avesse | fosse |
| noi | avessimo | fossimo |
| voi | aveste | foste |
| loro | avessero | fossero |
Choosing Avere vs. Essere
Just like in other compound tenses (such as the passato prossimo), verbs of motion, changes of state, and reflexive verbs take essere. For most other verbs, use avere.
Crucially, whenever you use essere as your helper, the past participle must agree in gender and number with the subject. With avere, the participle typically ends in the default -o.
Discussing the Forecast
Notice in the examples below how the past participle changes its ending for gender and number when essere is used, and remains unchanged with avere.