Introduction to Scripting - Python Trying to find Seasons [duplicate]

else is only attached to the last if-elif chain that precedes it. But since you didn't use elif the final else is only attached to the last if and will fire whenever the condition in that if is false regardless of the outcome of all other if conditions in your code.

There are many easier ways to do this rather than error-prone enumeration of each and every bound.

For example, you could use a dictionary keyed by month which returns a function that accepts day as its only argument and uses the value of day to compute the season:

seasons = {
    "January": lambda day: "Winter",
    "February": lambda day: "Winter",
    "March": lambda day: "Winter" if day < 21 else "Spring",
    "April": lambda day: "Spring",
    "May": lambda day: "Spring",
    "June": lambda day: "Spring" if day < 21 else "Summer",
    "July": lambda day: "Summer",
    "August": lambda day: "Summer",
    "September": lambda day: "Summer" if day < 22 else "Autumn",
    "October": lambda day: "Autumn",
    "November": lambda day: "Autumn",
    "December": lambda day: "Autumn" if day < 22 else "Winter",
}

Given this data structure, you can use it with seasons["March"](20).

Since you need to validate, I'd make that a distinct step. You can keep another dictionary that maps month names to integers representing their end date or number of days. Validation is then a matter of ensuring the key exists and that the day is >= 1 and <= days_by_month[some_month]. For example,

def validate(month, day):
    days_by_month = {
        "January": 31,
        "February": 28, # FIXME handle leap years
        "March": 31,
        # ... etc ...
    }
    return month in days_by_month and 1 <= day <= days_by_month[month]

validate("January", 31) # => True

Since February fluctuates, you may want to add an extra condition that uses the year to determine whether it's a leap year.

Use elif instead of if. Like this:

a = 200
b = 33
if b > a:
  print("b is greater than a")
elif a == b:
  print("a and b are equal")
else:
  print("a is greater than b")

The else statement at the end is only attached to the last if. You would want to use elif for the majority of the conditions:

input_month = input()
input_day = int(input())
months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December']

    
if (input_month in 'March') and (20 < input_day <= 31):
    print ('Spring')
elif (input_month in 'April') and (1 <= input_day <= 30): 
    print ('Spring')
elif (input_month in 'May') and (1 <= input_day <= 31):
    print ('Spring')
elif (input_month in 'June') and (1 <= input_day <= 20):
    print ('Spring')
    
elif (input_month in 'June') and (20 < input_day <= 30):
    print ('Summer')
elif (input_month in 'July') and (1 <= input_day <= 31):
    print ('Summer')
elif (input_month in 'August') and (1 <= input_day <= 31):
    print ('Summer')
elif (input_month in 'September') and (1 <= input_day < 21):
    print ('Summer')
    
elif (input_month in 'September') and (21 <= input_day <= 30):
    print ('Autumn')
elif (input_month in 'October') and (1 <= input_day <= 31):
    print ('Autumn')
elif (input_month in 'November') and (1 <= input_day <= 30):
    print ('Autumn')
elif (input_month in 'December') and (1 <= input_day < 21):
    print ('Autumn')  
    
elif (input_month in 'December') and (21 <= input_day <= 31):
    print ('Winter')
elif (input_month in 'January') and (1 <= input_day <= 31):
    print ('Winter')
elif (input_month in 'February') and (1 <= input_day <= 29):
    print ('Winter')
elif (input_month in 'March') and (1 <= input_day < 20):
    print ('Winter')
    
else: 
    print('Invalid')