My last trip to Brazil was like that. 4 weeks in the summer. It just rained, day and night. On the last day, it stopped raining, the sun shined bright and it was just wonderful.
I would ask my mum what a word meant and she'd ask me the context I'd read/heard it in, and then ask me what I thought it meant. She taught me to break the word up into syllables to see if there were other words I did know the definition of that shared those syllables and whether I could work it out from there.
If I couldn't then I had to look it up in the dictionary - we had a big, heavy Collins one from memory. Big blue hardback.
I remember being annoyed and just whining that she should just tell me the definition. But it was clearly better for me to learn that way.
Edit: I just re read and you said bad words. Mum would usually give me a clipped, child friendly definition and advice not to repeat it in polite company.
It’s not like you could go online. TV and newspapers had your local, but unless there was someone you could call, usually you had to chance it. Best you usually could do was pickup a newspaper from the store when you got there.
Earlier in the story arc they got to their campsite by canoe. In the 80s it's totally reasonable that they didn't know when the rain was going to break.