Number-guessing game in Python with a single level of abstraction
When too many parameters are being passed around, object-oriented programming can help.  But I don't think that that is your problem here.  I think you have divided the work into functions suboptimally.  Some advice:


Document each function's purpose in a docstring.

If you can't write a good docstring, then perhaps the function is poorly conceived.  Can you tell me what the displayHotHotterCooler() function does?  If you had to write a docstring for it, it might say:


  Assuming that a guess is hot, and that it is not the player's first guess, print 'HOT!!', 'HOTTER!!!', or 'COOLER' depending on how it rates relative to the previous guess.


That's too complicated, I think.  The function already has two preconditions on its applicability.  Any attempt to describe it better would end up being more verbose than the code itself.  Furthermore, the name displayHotHotterCooler doesn't really summarize the function's purpose.  All these problems suggest that this is not a worthwhile function to define, because its purpose is not clear.

In contrast, my display_hint() function below does have a clear summarizable purpose:


  Print a message hinting at the player's progress towards guessing the target number.

Delegate, don't micromanage.

promptGuess() could be smarter.  It already knows what the valid range is, so why can't it perform the validation for you too?  That would relieve main() from having to call validGuess(), and would eliminate one level of indentation from main().

Part of not micromanaging is to let each function figure out what information it needs.  Instead of passing three parameters newDistance, oldDistance, and firstGuess, consider passing the entire history of guesses instead, as a list.  The called function can infer whether it's the first guess based on the length of the array.  It can easily extract the last two elements, as needed.  (Drawbacks are that you end up storing more state than is strictly necessary, and that you have to trust the called function not to mutate the list.  But I think it's a worthwhile tradeoff for simplicity.)


Suggested solution

from random import randrange

def user_guesses(lo, hi):
    """
    Yield prompted guesses from the user, all verified to be integers
    between lo and hi (inclusive).
    """
    while True:
        guess = int(input('Enter a number ({}-{}): '.format(lo, hi)))
        if lo &lt;= guess &lt;= hi:
            yield guess

def display_win(diffs):
    """
    Print a congratulatory message for winning.
    """
    if len(diffs) == 1:
        print('WOW!! You got it on your first try!')
    else:
        print('GOOD JOB! You got it in {} tries.'.format(len(diffs)))

def display_hint(diffs, hot_distance):
    """
    Print a message hinting at the player's progress towards guessing
    the target number.

    diffs is a sequence of absolute differences between the guesses
    and the target number.  hot_distance is the threshold distance
    for considering a guess to be "hot".
    """
    is_hot = diffs[-1] &lt;= hot_distance
    was_hot = diffs[-2] &lt;= hot_distance if len(diffs) &gt; 1 else None
    if was_hot is None:
        print('HOT!' if is_hot else 'Cold')
    elif diffs[-1] == diffs[-2]:
        print('Same temperature!')
    elif is_hot:
        print('HOT!!' if not was_hot else
              'HOTTER!!!' if diffs[-1] &lt; diffs[-2] else
              'COOLER')
    else:
        print('COLD' if was_hot else
              'Warmer!' if diffs[-1] &lt; diffs[-2] else
              'Colder')

def main(lo=1, hi=100):
    """
    Pick a random number between lo and hi (inclusive), and let the
    player guess the number.  Temperature hints are printed until
    the player guesses correctly.
    """
    hot_distance = (hi - lo + 1) // 10      # 10% of the range
    answer = randrange(lo, hi + 1)
    diffs = []
    for guess in user_guesses(lo, hi):
        diffs.append(abs(guess - answer))
        if guess == answer:
            display_win(diffs)
            return
        display_hint(diffs, hot_distance)

main()


Other remarks:


Using the is operator to test for numeric equality is incorrect.  It only happens to work for some smaller numbers.

&gt;&gt;&gt; 5 is -(-5)
True
&gt;&gt;&gt; 1024 is -(-1024)
False
&gt;&gt;&gt; 5 == -(-5)
True
&gt;&gt;&gt; 1024 == -(-1024)
True

PEP 8, the official Python style guide, discourages extra spaces for the sake of aligning = signs.  It also recommends lower_case_with_underscores instead of interCaps naming.
Python support double-ended inequalities (lo &lt;= num &lt;= hi).
Instead of sprinkling references everywhere to hard-coded constants, I often prefer to define default parameters.
Flag variables, like won and isFirstTry, are almost always a sign that you can devise a better control structure.  Just eliminate them from your code.