Here's the composite precip anomalies for all developing moderate or stronger first year Nino Julys since 1950. Definitely a wetter signal for WA than OR.
It's a fairly small sample size for ginormo NiƱos and of course our temp baseline is much higher now, but in both 1982 and 2015 we saw pretty prolonged heat episodes in early to mid June but no major heat beforehand.
In both cases we also saw very dry Mays like this year.
May 1997 was really warm and dry early on before flipping to wet and active at the end. Summer 1997 stayed temperate and humid throughout, probably the stickiest summer I've seen here.
All three years gave us some pretty decent plumes of monsoonal moisture. The subtropical Eastern Pacific is probably going to be chomping at the bit by late July and rearing to go. We should see some pretty noteworthy storms and precip anomalies across the West in August and September. All three of 1982, 1997, and 2015 pulled that off and had extremely active EPAC hurricane seasons. With the warmer SSTAs now it should be bananas.
Historically, it's a pretty mixed bag even for July with developing Ninos. Of course 2023 is most fresh on people's minds, but past major +ENSO summers like 1997, 1986, 1983, 1982, 1972, 1965, and 1963 all had average to wet Julys for much of the region.
Since July has been bone dry overall regardless of ENSO lately (last July was actually PDX's second wettest in the past 10 years), I'm not sure that this year's ENSO situation is that meaningful...though if Phil and others are correct that we're moving into a new regime, that may be more at play.