Maybe you have too many individual months so that the labels are overlapping try setting date_breaks = "6 month" and rotating the labels with the theme function as I did in the code below.
DF <- data.frame(Date = seq.Date(from = as.Date("2020-01-01"),
to = as.Date("2020-12-31"), by = "day"),
Average = runif(n = 366, min = 10, max = 200))
library(ggplot2)
ggplot(DF, aes(Date, Average)) + geom_point() +
scale_x_date(date_breaks = "6 month", date_labels = "%B") +
theme(axis.text.x = element_text(angle = 90, hjust = 0.5, vjust = 0.5))

Created on 2020-01-26 by the reprex package (v0.3.0)