The Temperatures from OpenWeatherMap are always not in the List around last half Hour of the day.
Yesterday
https://pvoutput.org/intraday.jsp?id=64909&sid=57693&dt=20190710&gs=0&m=0
A few weeks ago
https://pvoutput.org/intraday.jsp?id=64909&sid=57693&dt=20190412
Hi yes you are right. on O W M website it says depending were you are currant forecasts may not be available for between 20 mins and 1 hour
The problem with OWM is they only provide current temperature, if a reading is missed or not recorded then there will be gaps in the data.