Small Aircraft; High Wing; 1 Eng; Fixed Gear
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 10; Flight Crew Total 2800; Flight Crew Type 800
Confusion; Time Pressure; Distraction; Situational Awareness
Airspace Violation All Types; Inflight Event / Encounter VFR In IMC; Inflight Event / Encounter Weather / Turbulence
Flight Crew Diverted
Human Factors; Weather
I departed ZZZ1 in VFR conditions for a four day camping trip.  Our destination was a USFS wilderness airstrip. There were TFRs for fire fighting in the general area of our destination; but it was not along the route of flight which is direct except for maneuvering to land in the canyon where the airport is located. The weather forecast for the next four days was clear. The morning of the return flight; from ZZZ to ZZZ1; there was smoke at ZZZ but visibility was about seven miles.  Aircraft which had departed a nearby airstrip were easily visible overhead. I chose to depart to the southwest following a river expecting to find improving conditions as we moved away from a wildfire. We flew down the canyon but visibility deteriorated to MVFR. Attempting to climb over the smoke would result in losing visual contact with the ground and I did not attempt it.Visibility deteriorated to about one mile. Nearby airports were reporting visibility of 1 sm and 3/4 sm respectively so I did not divert there. I began following the interstate highway. Conditions deteriorated again and we descended further to keep the highway in view. We received the ASOS and it reported 1/2 sm; so we continued towards our destination. When we first received the destination ASOS the reported visibility that sounded like 1/8 mile. At that point; I turned around and headed to ZZZ2 to land visually which was uneventful. After landing at ZZZ2 I saw the visibility was reported as 1 sm at ZZZ1 but we had already landed safely. We rented a car and drove the rest of the way.The smoke had forced me to fly a different route than I planned. It kept us confined to a river valley where a TFR was located although I do not know if we flew through the TFR. The flight conditions were mostly MVFR but the airports were reporting IFR and LIFR; so we elected to continue the flight VFR. The flight conditions worsened further and I elected to make a visual approach and landing when the ASOS was reporting 1/2 sm visibility.Looking back at the chain of events there were several factors that led to me making this flight under these conditions. The forecast available on our departure made no mention of smoke or limited visibility and our return was four days later. The level of smoke was reported to be the most ever recorded in the region. Throughout the flight I made what appeared to be the best choice based on my knowledge of conditions to that point. Those choices led me to worse conditions and worse choices. I considered contacting ATC and requesting an IFR clearance but didn't due to not being IFR current and not having procedure charts with me. In retrospect I should have declared an emergency and requested ATC assistance rather than continuing into deteriorating conditions. A solution would have been a satellite modem to get weather information in the remote location.
A pilot flying VFR encountered IFR conditions due to unexpected smoke from wildfires.