I have exactly the same automations. Some of it is in Dutch… I have it running for a couple of weeks and with the heat in the Netherlands it is working perfect! I also have a window-sensor, so only get the relevant message 
But I use the difference in temperature for my triggers:
Automations:
- alias: Bericht sturen als buiten kouder dan kamer en binnen >20 graden
trigger:
- platform: numeric_state
entity_id: sensor.delta_temp_kamer
above: 1
for:
minutes: 10
condition:
condition: and
conditions:
- condition: numeric_state
entity_id: sensor.netatmo_kamer_temperature_2
above: 20
- condition: state
entity_id: binary_sensor.window_sensor_1
state: 'off'
action:
- service: notify.telegram_me
data_template:
message: '*Het is nu buiten {{ states.sensor.delta_temp_jasper.state }} graden kouder dan binnen in de kamer waar het {{ states.sensor.netatmo_jasper_kamer_temperature_2.state }} graden is, tijd om het raam open te zetten*'
- alias: Bericht sturen als buiten warmer is dan de kamer en buiten >20 graden
trigger:
- platform: numeric_state
entity_id: sensor.delta_temp_kamer
below: -0.5
for:
minutes: 10
condition:
condition: and
conditions:
- condition: numeric_state
entity_id: sensor.rotterdam_temperature
above: 20
- condition: state
entity_id: binary_sensor.window_sensor_1
state: 'on'
action:
- service: notify.telegram_me
data_template:
message: '*Het is nu buiten {{ (float(states.sensor.delta_temp_jasper.state))*-1 }} graden warmer dan binnen in kamer waar het {{ states.sensor.netatmo_jasper_kamer_temperature_2.state }} graden is, tijd om het raam dicht te doen*'
Template for delta temp:
- platform: template
sensors:
delta_temp_kamer:
value_template: '{{ ((float(states.sensor.netatmo_kamer_temperature_2.state)) - (float(states.sensor.rotterdam_temperature.state))) | round(2) }}'
unit_of_measurement: 'Graden'
friendly_name: 'Delta temp Kamer Binnen - buiten'
icon_template: "mdi:thermometer"