Highcharts
CodePen jsFiddle 
Date,Average temperature
2021-01-01,-1.76667
2021-01-02,-2.32083
2021-01-03,-7.03333
2021-01-04,-8.62917
2021-01-05,-7.82500
2021-01-06,-10.00000
2021-01-07,-8.72500
2021-01-08,-10.26190
2021-01-09,-3.74783
2021-01-10,-1.00417
2021-01-11,-3.10833
2021-01-12,-0.77917
2021-01-13,-3.94167
2021-01-14,-11.97917
2021-01-15,-13.50417
2021-01-16,-12.25417
2021-01-17,-2.50833
2021-01-18,-1.40833
2021-01-19,-2.34583
2021-01-20,-0.60000
2021-01-21,1.23750
2021-01-22,2.47917
2021-01-23,2.97917
2021-01-24,-1.20000
2021-01-25,-5.55833
2021-01-26,-3.57500
2021-01-27,-11.29583
2021-01-28,-10.21667
2021-01-29,-7.45000
2021-01-30,-4.18333
2021-01-31,-3.07083
2021-02-01,-10.80833
2021-02-02,-10.42917
2021-02-03,-14.70000
2021-02-04,-15.12917
2021-02-05,-13.62917
2021-02-06,-12.11250
2021-02-07,-12.64583
2021-02-08,-11.81250
2021-02-09,-11.12500
2021-02-10,-12.95000
2021-02-11,-13.09167
2021-02-12,-14.72917
2021-02-13,-14.55833
2021-02-14,-11.65417
2021-02-15,-2.02500
2021-02-16,-0.33333
2021-02-17,0.37083
2021-02-18,0.45417
2021-02-19,3.64167
2021-02-20,2.72083
2021-02-21,6.60000
2021-02-22,3.34583
2021-02-23,3.80000
2021-02-24,6.69583
2021-02-25,6.01250
2021-02-26,5.45417
2021-02-27,5.11250
2021-02-28,5.93750
2021-03-01,6.58750
2021-03-02,5.30000
2021-03-03,4.48333
2021-03-04,0.58333
2021-03-05,1.81250
2021-03-06,2.96842
2021-03-07,1.59583
2021-03-08,-1.25000
2021-03-09,1.71250
2021-03-10,1.65833
2021-03-11,4.10417
2021-03-12,2.70833
2021-03-13,3.00833
2021-03-14,2.38750
2021-03-15,1.72917
2021-03-16,2.56667
2021-03-17,1.14583
2021-03-18,2.99583
2021-03-19,3.06250
2021-03-20,5.60833
2021-03-21,4.17917
2021-03-22,6.09583
2021-03-23,7.60833
2021-03-24,6.89167
2021-03-25,5.01667
2021-03-26,5.49167
2021-03-27,6.05417
2021-03-28,5.11739
2021-03-29,6.66667
2021-03-30,5.45833
2021-03-31,6.50833
2021-04-01,3.09583
2021-04-02,5.50000
2021-04-03,4.65417
2021-04-04,5.81250
2021-04-05,-0.57500
2021-04-06,1.17083
2021-04-07,3.43750
2021-04-08,0.61667
2021-04-09,1.34583
2021-04-10,1.50435
2021-04-11,1.63333
2021-04-12,3.64167
2021-04-13,3.67500
2021-04-14,4.11667
2021-04-15,3.35833
2021-04-16,4.44583
2021-04-17,5.17083
2021-04-18,7.66250
2021-04-19,8.52083
2021-04-20,6.90455
2021-04-21,5.35833
2021-04-22,5.16667
2021-04-23,5.28261
2021-04-24,4.23182
2021-04-25,3.38333
2021-04-26,3.61667
2021-04-27,4.58333
2021-04-28,4.59583
2021-04-29,5.36818
2021-04-30,6.86000
2021-05-01,6.71250
2021-05-02,7.55000
2021-05-03,6.30833
2021-05-04,5.80417
2021-05-05,9.35909
2021-05-06,6.66190
2021-05-07,7.77391
2021-05-08,5.76667
2021-05-09,6.40435
2021-05-10,9.03333
2021-05-11,14.46667
2021-05-12,11.57917
2021-05-13,13.83333
2021-05-14,14.85417
2021-05-15,15.75833
2021-05-16,11.58333
2021-05-17,11.74583
2021-05-18,9.90000
2021-05-19,10.71176
2021-05-20,9.99583
2021-05-21,9.04583
2021-05-22,11.70833
2021-05-23,13.39167
2021-05-24,12.71250
2021-05-25,12.60417
2021-05-26,14.25833
2021-05-27,13.32500
2021-05-28,13.98750
2021-05-29,15.95417
2021-05-30,15.15000
2021-05-31,15.47083
2021-06-01,17.25833
2021-06-02,18.41667
2021-06-03,18.64583
2021-06-04,17.09167
2021-06-05,18.32917
2021-06-06,16.62083
2021-06-07,17.65000
2021-06-08,16.47500
2021-06-09,15.96667
2021-06-10,14.24583
2021-06-11,15.73333
2021-06-12,10.51250
2021-06-13,10.41667
2021-06-14,10.74583
2021-06-15,10.22500
2021-06-16,9.08333
2021-06-17,11.89583
2021-06-18,13.49583
2021-06-19,11.72917
2021-06-20,13.38333
2021-06-21,12.94167
2021-06-22,15.00417
2021-06-23,13.99167
2021-06-24,16.13750
2021-06-25,17.58333
2021-06-26,17.73750
2021-06-27,16.88333
2021-06-28,15.80000
2021-06-29,16.02917
2021-06-30,18.02083
2021-07-01,18.55000
2021-07-02,19.48750
2021-07-03,20.03333
2021-07-04,18.62500
2021-07-05,19.70500
2021-07-06,19.27619
2021-07-07,17.02083
2021-07-08,17.06667
2021-07-09,16.85000
2021-07-10,17.90417
2021-07-11,17.07917
2021-07-12,17.67083
2021-07-13,19.02500
2021-07-14,19.47917
2021-07-15,17.17083
2021-07-16,14.87083
2021-07-17,17.50000
2021-07-18,12.97083
2021-07-19,15.50526
2021-07-20,14.50000
2021-07-21,15.48333
2021-07-22,15.54583
2021-07-23,18.31250
2021-07-24,18.99583
2021-07-25,19.71667
2021-07-26,20.89167
2021-07-27,21.25417
2021-07-28,18.64500
2021-07-29,17.94783
2021-07-30,19.50000
2021-07-31,14.60417
2021-08-01,16.22083
2021-08-02,15.12917
2021-08-03,13.83750
2021-08-04,13.72083
2021-08-05,14.88333
2021-08-06,17.10000
2021-08-07,18.49167
2021-08-08,16.83750
2021-08-09,15.12917
2021-08-10,16.29583
2021-08-11,14.60000
2021-08-12,18.18667
2021-08-13,14.20417
2021-08-14,14.21667
2021-08-15,13.71667
2021-08-16,14.25000
2021-08-17,15.06667
2021-08-18,13.77917
2021-08-19,13.81250
2021-08-20,13.69583
2021-08-21,12.02083
2021-08-22,12.96667
2021-08-23,13.82917
2021-08-24,13.25833
2021-08-25,15.85833
2021-08-26,14.52083
2021-08-27,13.65833
2021-08-28,13.19583
2021-08-29,13.70417
2021-08-30,13.88333
2021-08-31,14.82174
2021-09-01,14.10000
2021-09-02,14.30000
2021-09-03,13.83750
2021-09-04,11.16250
2021-09-05,13.15833
2021-09-06,13.93333
2021-09-07,13.75417
2021-09-08,15.91250
2021-09-09,16.09167
2021-09-10,15.10833
2021-09-11,15.22917
2021-09-12,15.60417
2021-09-13,10.30417
2021-09-14,9.55833
2021-09-15,10.35417
2021-09-16,12.03333
2021-09-17,12.70000
2021-09-18,9.89167
2021-09-19,12.85833
2021-09-20,11.89167
2021-09-21,10.78750
2021-09-22,12.09167
2021-09-23,9.47083
2021-09-24,7.86250
2021-09-25,9.80000
2021-09-26,11.10833
2021-09-27,13.31250
2021-09-28,11.14583
2021-09-29,11.16250
2021-09-30,11.93750
2021-10-01,10.25000
2021-10-02,8.85833
2021-10-03,10.96250
2021-10-04,11.20417
2021-10-05,9.13333
2021-10-06,7.90000
2021-10-07,8.33333
2021-10-08,10.46667
2021-10-09,12.28333
2021-10-10,10.69167
2021-10-11,6.72500
2021-10-12,6.29583
2021-10-13,4.00000
2021-10-14,8.71250
2021-10-15,6.77500
2021-10-16,5.68333
2021-10-17,3.45833
2021-10-18,0.60417
2021-10-19,3.91667
2021-10-20,7.78750
2021-10-21,4.41667
2021-10-22,4.26250
2021-10-23,5.68333
2021-10-24,5.30833
2021-10-25,7.20417
2021-10-26,6.47083
2021-10-27,6.76667
2021-10-28,8.37500
2021-10-29,8.83333
2021-10-30,9.00833
2021-10-31,8.48696
2021-11-01,8.42500
2021-11-02,9.20417
2021-11-03,5.43750
2021-11-04,0.62083
2021-11-05,4.00417
2021-11-06,4.64167
2021-11-07,4.04167
2021-11-08,3.85417
2021-11-09,5.41667
2021-11-10,7.42083
2021-11-11,6.25909
2021-11-12,NULL
2021-11-13,NULL
2021-11-14,0.00000
2021-11-15,2.58333
2021-11-16,6.57083
2021-11-17,5.28333
2021-11-18,3.52500
2021-11-19,8.61250
2021-11-20,4.80417
2021-11-21,1.78750
2021-11-22,4.64583
2021-11-23,5.83333
2021-11-24,6.12917
2021-11-25,2.42083
2021-11-26,-2.40870
2021-11-27,-3.24167
2021-11-28,-7.52083
2021-11-29,-6.89167
2021-11-30,-3.58333
2021-12-01,-7.02083
2021-12-02,-5.12083
2021-12-03,-6.22500
2021-12-04,-4.77500
2021-12-05,-6.47500
2021-12-06,-6.45000
2021-12-07,-3.98750
2021-12-08,-2.00833
2021-12-09,-3.21250
2021-12-10,-4.46250
2021-12-11,-4.74583
2021-12-12,0.67500
2021-12-13,3.20000
2021-12-14,3.61667
2021-12-15,5.53750
2021-12-16,5.40833
2021-12-17,4.93333
2021-12-18,6.36667
2021-12-19,3.01250
2021-12-20,-1.37083
2021-12-21,-1.80000
2021-12-22,-0.04583
2021-12-23,-1.73333
2021-12-24,-5.65417
2021-12-25,-2.48333
2021-12-26,-0.73043
2021-12-27,-6.98750
2021-12-28,-1.59583
2021-12-29,-1.72083
2021-12-30,0.75000
2021-12-31,3.01250