Aggregate multiple points on same date/time

I’m using Grafana 5.4.3 and InfluxDB 1.7.3.

In this chart I’m receiving multiple points for the same time and date. How can I get a mean of those three points so that my chart is plotting only that single mean?

When I apply mean() in the SELECT statement the chart displays only a single point for one day even if the range is now-3d - now+3d.

> select temperatureHigh from darksky_daily
name: darksky_daily
time                 temperatureHigh
----                 ---------------
2019-02-20T08:00:00Z 55.38
2019-02-21T08:00:00Z 57.12
2019-02-21T08:00:00Z 56.99
2019-02-22T08:00:00Z 57.48
2019-02-22T08:00:00Z 55.54
2019-02-22T08:00:00Z 56.82
2019-02-23T08:00:00Z 54.94
2019-02-23T08:00:00Z 54.62
2019-02-23T08:00:00Z 56.03
2019-02-23T08:00:00Z 55.85
2019-02-24T08:00:00Z 54.92
2019-02-24T08:00:00Z 53.85
2019-02-24T08:00:00Z 53.98
2019-02-24T08:00:00Z 51.87
2019-02-25T08:00:00Z 54.65
2019-02-25T08:00:00Z 53.25
2019-02-25T08:00:00Z 55.44
2019-02-25T08:00:00Z 54.64
2019-02-26T08:00:00Z 55.6
2019-02-26T08:00:00Z 56.2
2019-02-26T08:00:00Z 54.99
2019-02-26T08:00:00Z 55.21
2019-02-27T08:00:00Z 54.65
2019-02-27T08:00:00Z 55.73
2019-02-27T08:00:00Z 59.28
2019-02-27T08:00:00Z 58.06
2019-02-28T08:00:00Z 55.79
2019-02-28T08:00:00Z 59.8
2019-02-28T08:00:00Z 57.18
2019-03-01T08:00:00Z 55.5
2019-03-01T08:00:00Z 52.41
2019-03-02T08:00:00Z 53.52