Comment by qwertox

What is your problem with this example, doesn't it get the job done?

  WITH temperatures AS ( /* ... */ )
  SELECT
      *,
      MAX(c) OVER (
          ORDER BY t
          ROWS BETWEEN 2 PRECEDING AND CURRENT ROW
      ) AS hottest_temperature_last_three_days
  FROM
      temperatures;
  
       t      │ c  │ hottest_temperature_last_three_days
  ────────────┼────┼─────────────────────────────────────
   2021-01-01 │ 10 │                                  10
   2021-01-02 │ 12 │                                  12
   2021-01-03 │ 13 │                                  13
   2021-01-04 │ 14 │                                  14
   2021-01-05 │ 18 │                                  18
   2021-01-06 │ 15 │                                  18
   2021-01-07 │ 16 │                                  18
   2021-01-08 │ 17 │                                  17

Why should I fetch all the data and then form the result with another tool?

What a great article.