When the nostrils are widened it allows more air to be breathed in and out and readies the person for combat. In a related sense, this can indicate the person is experiencing extreme displeasure.
Flared nostrils may also indicate that the person is making an internal judgment about something.
Aside from when a person has a cold, sniffing can indicate displeasure or disgust. This may also happen on one side, with the mouth twitching up as well..
The nose can be wrinkled by pushing up from the mouth, pushing the cheeks or pulling from the top. This happens when a bad smell is detected. It can also appear with a metaphoric bad smell is thought about, for example when somebody else suggests a distasteful idea (see: even language uses bad-taste metaphor!). Card players may do this, for example, when they are dealt a bad hand.
Another variation is when the person is thinking about something but is not satisfied with their own ideas.
If however your nose has sinus problems due to the change in season, it's important that you visit your nearest Doctor at Peermed