The weatherData package, link , makes it very easy to retrieve detailed weather data from hundreds of stations across the US. I developed this script to retrieve and plot daily maximum and minimum temperatures and highlight days with 90+ max temps and 75+ minimum temps. Here’s the results of my script:

The user can specify the desired weather station and can change to the year to examine earlier times or the current year.

Here is the R script:

## Hot Days and nights this summer
## use weatherData package to retrieve Max & Min temperature data for summer months
## User can specify airport code, query will use this code to retrieve current yrs data 
library(weatherData)
  hot_days <- numeric()
  hot_nights <- numeric()
### Enter airport Code and year ##############  
  airport <- "KPNE"
  my_yr <- 2016
##############################################  
  my_start <- paste(my_yr,"-05-01",sep="")
  ## calc current date for data query
    end_date <- format(Sys.Date() -1, "-%m-%d")
    my_end <- paste(my_yr,end_date,sep="")
#### Retrieve data from Weather Underground   
  df <-  getWeatherForDate(airport,start_date=my_start,end_date= my_end,opt_detailed=F, opt_all_columns=F)
  hot_df <- subset(df, df$Max_TemperatureF>89)
  hot_days <- nrow(hot_df)
  hot_nights_df <- subset(df, df$Min_TemperatureF>75)
  hot_nights <- nrow(hot_nights_df)
  hot_day_note <- paste(hot_days, " days with 90+ temp through ",format(Sys.Date()-1,"%m/%d"), sep="")
  hot_nights_note <- paste(hot_nights, " nights with 75+ temp")

  y_lab <- expression(paste("Temperature - ", degree, "F"),sep="")
  title <- paste("Hot Days and Nights This Summer \nMax & Min Temperatures @ ",airport, "\n ",my_yr)

  ## Use plot function to allow both png file and console output of plot
 plot_func <- function() {    
  par(las=1)
  plot(df$Date, df$Max_TemperatureF,type="l", ylim =c(50,100),main=title,
       xlab="", ylab=y_lab) 
  abline(h=90, col="red")
  abline(h = 75, col = "blue")
  points(hot_df$Date, hot_df$Max_TemperatureF, type="p",pch=19, col = "red")
  text (df$Date[10], 98, hot_day_note, col = "red", adj=0)
  text (df$Date[10], 96, hot_nights_note, col = "blue", adj=0)
  points(df$Date,  df$Min_TemperatureF, col="blue", type="l")
  points(hot_nights_df$Date, hot_nights_df$Min_TemperatureF, type="p", pch=19, col="blue")
 
  legend(df$Date[75],67, c("Daily Max Temp", "Daily Min Temp", "Daily Max 90 or more", "Daily Min 75 or more" ), 
         col = c("black", "blue","red", "blue"),
         text.col = "black", lty = c(1,1,0,0),lwd = c(2.5,2.5,0,0),seg.len=1, pch=c(0,0,19,19),pt.cex=c(0,0,1,1),
         merge = T, bg = "", bty="n", box.col = "white", cex = .7, ncol=1)
  }

 # Output to png file and plot to console
  png(file= "F:\\RClimate.us\\RClimate_Posts\\KPNE_Summer_hot_days.png", width=600, height=500)
  plot_func() 
  dev.off()
  plot_func()