SQL Server 2019

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CREATE TABLE #AvgTemperatures(
   id     INTEGER  NOT NULL 
  ,city   VARCHAR(11) NOT NULL
  ,[avg]    INTEGER  NOT NULL
  ,months INTEGER  NOT NULL
);
INSERT INTO #AvgTemperatures(id,city,avg,months) VALUES (1,'New-York',20,3);
INSERT INTO #AvgTemperatures(id,city,avg,months) VALUES (2,'New-York',19,6);
INSERT INTO #AvgTemperatures(id,city,avg,months) VALUES (3,'New-York',15,12);
INSERT INTO #AvgTemperatures(id,city,avg,months) VALUES (4,'New-York',15,24);
INSERT INTO #AvgTemperatures(id,city,avg,months) VALUES (5,'Boston',13,3);
INSERT INTO #AvgTemperatures(id,city,avg,months) VALUES (6,'Boston',18,8);
INSERT INTO #AvgTemperatures(id,city,avg,months) VALUES (7,'Boston',17,12);
INSERT INTO #AvgTemperatures(id,city,avg,months) VALUES (8,'Boston',16,15);
INSERT INTO #AvgTemperatures(id,city,avg,months) VALUES (9,'Chicago',12,2);
INSERT INTO #AvgTemperatures(id,city,avg,months) VALUES (10,'Chicago',14,12);
INSERT INTO #AvgTemperatures(id,city,avg,months) VALUES (11,'Miami',28,1);
INSERT INTO #AvgTemperatures(id,city,avg,months) VALUES (12,'Miami',25,4);
INSERT INTO #AvgTemperatures(id,city,avg,months) VALUES (13,'Miami',21,12);
INSERT INTO #AvgTemperatures(id,city,avg,months) VALUES (14,'Miami',22,15);
INSERT INTO #AvgTemperatures(id,city,avg,months) VALUES (15,'Miami',20,24);

;WITH cte AS
(
  SELECT t.*, MAX(AVG) OVER (PARTITION BY city) AS average
  FROM #avgTemperatures t
)
SELECT *
FROM cte
where average > 19
ORDER BY id

id	city	avg	months	average
1	New-York	20	3	20
2	New-York	19	6	20
3	New-York	15	12	20
4	New-York	15	24	20
11	Miami	28	1	28
12	Miami	25	4	28
13	Miami	21	12	28
14	Miami	22	15	28
15	Miami	20	24	28