La Crosse Technology WS-7213U Instruction Manual page 6

In this time the indoor weather station and
remote temp/humidity sensor will start to
talk to each other and the displays will show
both the indoor temperature and an outdoor
temperature and humidity. If the indoor
weather station do not display both the
indoor temperature and the outdoor
temperature and humidity after the 15
minutes please retry the set up as shown on
page five.
After both indoor temperature and outdoor
temperature and humidity are displayed for
10 minutes you can place your remote
temp/humidity sensor outdoors and set your
time.
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