Complex sentence: The city possesses a microclimate and is considered the region least subject to frosts in all northern Portugal, and very uncommon snowfall, the last occurred in January 1986, inland snowfall occurred more recently.
Split into simpler sentences: The city possesses a microclimate and is considered the region least subject to frosts in all northern Portugal. Cold waves are absent and snowfall is very uncommon, the last occurred in January 1986, inland snowfall occurred more recently.