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Exercise20 min

Exercise: A week of weather

The temperatures of a week are in a list. The program sums them up, takes in a new reading and shows how the picture changes.

Programming with Python

See first: Lists

What you will learn

In this exercise you analyse the temperatures of a week, and afterwards you can:

  • sum up a list of readings with min(), max(), sum() and len()
  • print the first and the last value of a list with [0] and [-1]
  • convert an input value with float() and add it to the list with append()
  • print the values in order with sorted() without changing the list itself
  • print decimal numbers with one decimal place using :.1f in an f-string

Download as a script python-exercise-weather.py with the task as comments, to run in VS Code or Positron

Task

A weather station measured the temperature at noon on seven days; the values are already in the program. Write a program that prints how many readings there are, which value stood at the start and which at the end of the week, how warm it was at most and at least, and how high the average is. After that it asks for today's reading, adds it to the list and prints the new average and all values by size.

What it should look like

7 readings
First day: 12.5 degrees, last day: 15.5 degrees
At most 18.0 degrees, at least 9.5 degrees
Average: 13.4 degrees
Temperature today? 21
Now 8 readings, average: 14.4 degrees
By size: [9.5, 11.0, 12.5, 13.5, 14.0, 15.5, 18.0, 21.0]

Your program

temperatures = [12.5, 14.0, 9.5, 18.0, 13.5, 11.0, 15.5]

# How many values, first and last, highest and lowest, average?

# Ask for today's value and add it, then analyse again
SHOW HINT 1

No function of its own gives the average: divide the sum by the number of values, that is sum(temperatures) / len(temperatures). With :.1f in the f-string it appears with one decimal place.

SHOW HINT 2

input() returns text. For it to go into the list as a number, convert it with float() before you add it with append(). After adding, the list is one element longer, and len() and sum() see the new value by themselves.

SHOW THE SOLUTION 
temperatures = [12.5, 14.0, 9.5, 18.0, 13.5, 11.0, 15.5]

average = sum(temperatures) / len(temperatures)
print(f"{len(temperatures)} readings")
print(f"First day: {temperatures[0]} degrees, last day: {temperatures[-1]} degrees")
print(f"At most {max(temperatures)} degrees, at least {min(temperatures)} degrees")
print(f"Average: {average:.1f} degrees")

today = float(input("Temperature today? "))
temperatures.append(today)

average = sum(temperatures) / len(temperatures)
print(f"Now {len(temperatures)} readings, average: {average:.1f} degrees")
print(f"By size: {sorted(temperatures)}")

The average is worked out again after adding, because the variable average still holds the old value: it remembered the number, not the calculation. And because sorted() returns a new list, temperatures keeps the order of the measuring days.

For the quick ones

Also print on which day it was warmest. temperatures.index(value) returns the position at which a value first occurs; add one so that the first day is called day 1 and not day 0.

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Details
Level
Beginner
Modules
Digitization and Programming
In learning paths
Python for beginners
Code
7488
Updated
1 November 2026
Status
published

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