• Phoenix is one of the hottest cities in the united states
• Is phoenix actually getting hotter over time?
• I will use a simple linear regression on the data to find out

• My source is the National Centers for Environmental Information
• Average yearly temperature in Phoenix from 1934 to 2025
• Chart: NOAA Climate at a Glance

• We draw the best straight line through the recorded temperatures
• The slope of that line tells us how much Phoenix becomes hotter each year
• If the slope is positive this means that Phoenix is getting hotter

\[ Average = (High + Low) / 2 \]

• Each day, the high and low temperatures are averaged

\[ Yearly = (Jan + Feb + ... + Dec) / 12 \]

• The 12 monthly averages are averaged to get one number per year

• The blue line rises about 0.05°F per year so 0.5°F per decade

• The dotted line is the average temperature for all years (75.1°F)

g <-ggplot(phx_clean, aes(x =Year, y=Value)) +
  geom_point()

g +
  geom_smooth(method ="lm", se =FALSE) +
  theme_classic()+

  xlab("Year") +
  ylab("Average Temperature (F)")

• phoenix tempreture has increased 0.5F every decade
• this is almost 5F warmer since 1934
• the most recent years are above the long term average
• so yes phoenix is getting hotter