Plotting two graphs into the same one

Hi y'all!

I have to plot the monthly and minimum temperature into a same graph. RIght now, I managed to put them on different graphes.. Apparently I have to create one sigle variable x for both but not sure how to do that.

Thanks for helping me!

Month Day Year AvgTemperature       Date

1: 1 1 2015 62.4 2015-01-01
2: 1 2 2015 60.4 2015-01-02
3: 1 3 2015 63.0 2015-01-03
4: 1 4 2015 67.4 2015-01-04
5: 1 5 2015 69.4 2015-01-05

1823: 12 27 2019 64.7 2019-12-27
1824: 12 28 2019 66.7 2019-12-28
1825: 12 29 2019 66.1 2019-12-29

Hi!

I relized i gave you the wrong data set

here is the good one
year month MonthlyMax MonthlyMin Date
1: 2015 1 70.4 55.2 2015-01-01
2: 2015 2 74.7 56.3 2015-02-01
3: 2015 3 77.5 61.8 2015-03-01
4: 2015 4 82.9 63.1 2015-04-01
5: 2015 5 88.5 77.8 2015-05-01
6: 2015 6 89.5 83.9 2015-06-01
7: 2015 7 89.5 81.5 2015-07-01
8: 2015 8 91.9 81.0 2015-08-01
9: 2015 9 87.6 79.7 2015-09-01
10: 2015 10 85.1 69.6 2015-10-01
11: 2015 11 81.9 64.7 2015-11-01
12: 2015 12 75.6 -99.0 2015-12-01
13: 2016 1 72.0 40.2 2016-01-01
14: 2016 2 75.5 48.9 2016-02-01
15: 2016 3 76.2 -99.0 2016-03-01
16: 2016 4 82.9 71.0 2016-04-01
17: 2016 5 87.8 -99.0 2016-05-01
18: 2016 6 89.9 80.2 2016-06-01
19: 2016 7 91.7 83.0 2016-07-01
20: 2016 8 89.1 80.6 2016-08-01
21: 2016 9 90.4 -99.0 2016-09-01
22: 2016 10 85.6 75.7 2016-10-01
23: 2016 11 81.3 -99.0 2016-11-01
24: 2016 12 75.5 58.4 2016-12-01
25: 2017 1 73.5 58.4 2017-01-01
26: 2017 2 71.3 51.7 2017-02-01
27: 2017 3 75.4 60.9 2017-03-01
28: 2017 4 82.7 66.9 2017-04-01
29: 2017 5 85.8 75.9 2017-05-01
30: 2017 6 88.8 80.2 2017-06-01
31: 2017 7 92.0 79.5 2017-07-01
32: 2017 8 91.8 79.6 2017-08-01
33: 2017 9 88.8 82.2 2017-09-01
34: 2017 10 88.7 73.2 2017-10-01
35: 2017 11 79.7 63.7 2017-11-01
36: 2017 12 70.3 52.7 2017-12-01
37: 2018 1 70.4 -99.0 2018-01-01
38: 2018 2 71.8 49.8 2018-02-01
39: 2018 3 78.5 55.2 2018-03-01
40: 2018 4 81.2 63.1 2018-04-01
41: 2018 5 89.8 76.0 2018-05-01
42: 2018 6 87.9 81.3 2018-06-01
43: 2018 7 88.1 80.7 2018-07-01
44: 2018 8 88.9 81.7 2018-08-01
45: 2018 9 90.8 79.6 2018-09-01
46: 2018 10 82.1 72.2 2018-10-01
47: 2018 11 79.9 -99.0 2018-11-01
48: 2018 12 77.7 51.9 2018-12-01
49: 2019 1 71.2 -99.0 2019-01-01
50: 2019 2 74.9 60.5 2019-02-01
51: 2019 3 79.0 62.8 2019-03-01
52: 2019 4 84.8 -99.0 2019-04-01
53: 2019 5 85.6 -99.0 2019-05-01
54: 2019 6 88.9 81.4 2019-06-01
55: 2019 7 90.0 80.1 2019-07-01
56: 2019 8 90.1 80.4 2019-08-01
57: 2019 9 87.8 81.7 2019-09-01
58: 2019 10 87.3 74.5 2019-10-01
59: 2019 11 80.5 67.3 2019-11-01
60: 2019 12 74.7 60.7 2019-12-01

In the second data set that you posted, I see the MonthlyMax and MonthlyMin. Is it those two quantities that you want to put on one plot? What plotting function or package are you using?
Can you post the code you used to get the individual plots?