This extension adds some useful aggregation types to WeeWX, using the XTypes facility.

• Historical highs and lows for a date;
• The number of days above or below an average value.

Works for both SQLite and MySQL.

XAggs will only work with WeeWX V4.2 or later.

1. Download and install the extension

   cd /home/weewx
   wget https://github.com/tkeffer/weewx-xaggs/archive/master.zip
   wee_extension --install=weewx-xaggs.zip

2. Restart WeeWX. For example:

   sudo systemctl stop weewx
   sudo systemctl start weewx

After installation, these new aggregation types will be available:

For example, the following template

<p>Historically high temperature for this day: 
    $day.outTemp.historical_max in $day.outTemp.historical_maxtime.format("%Y")</p>
<p>Number of days this month with average temperature over 20&deg;C:
    $month.outTemp.avg_gt((20.0, 'degree_C', 'group_temperature'))</p> 

would result in something like:

Historically high temperature for this day: 64.8°F in 2013
Number of days this month with average temperature over 20°C: 11

Plots can also be made, which show historical highs and lows. For example, putting this plot specification under the [[monthimages]] section of skin.conf.

    [[monthimages]]

        ...

        [[[monthhistorical]]]
             [[[[min]]]]
                 label = min
                 aggregate_type = historical_min
                 aggregate_interval = day
                 data_type = outTemp
             [[[[outTemp]]]]
             [[[[max]]]]
                label = max
                aggregate_type = historical_max
                aggregate_interval = day
                data_type = outTemp

will result in a plot that looks something like this:

The only supported aggregation interval is one day. This means the historical_ aggregations can only be used with the $day tag, or in plots with an aggregation interval of one day.