R Language: How to Set ylim?

-60:10 generates a sequence from -60 to 10, what you need as the ylim is a min and max value (with syntax c(min, max)) instead of a sequence, try this:

ylim=c(-60,10)

You need to change it to

ylim=c(-60,10)

so the whole thing would be:

plot(BriannaJan[,3,i], type = "line", col="black", main ="Brianna January Trend",
   xlab = "days", ylab="Temperature", ylim=c(-60,10))