NAPERVILLE, Illinois, July 10 (Reuters) - The U.S. corn crop was seemingly fast-tracking to disaster last month amid historically dry weather, but July has so far featured a wetter and cooler pattern for many top-producing states, aiding in recovery.

Corn conditions have recently been comparable to the drought-stricken 2012 season, though they U-turned at the start of July. The Department of Agriculture as of Sunday rated 55% of U.S. corn as good or excellent (GE), up from 51% in the prior week and above the trade guess of 53%.

Corn conditions tend to stay largely unchanged or decline slightly throughout the season even in high-yielding years, so this week’s increase stands out. The last time corn conditions improved 4 or more percentage points in a late-June or early-July week was in 2001, and there were four more instances between 1992 and 1997.

However, it is also rare to see corn ratings this low in early July. Sunday’s 55% GE is the worst for the week since 40% in 2012, and the last time the week's rating was worse than now was in 2002 at 53%.

Analysts will forever attempt to make connections between crop conditions and yield, which can be valid depending on the goal, though the connections must be carefully interpreted.

An example of a more qualitative observation looks at relative yield outcomes. In the last 37 years, there were only seven years where corn was less than 60% GE in the week centered on July 8 (week 27). Yield was above trend in one of those years, equal to trend in another but below it in the remaining five years.

That gives a possible lean on 2023 but does not rule out an average or above-trend result.

A quantitative approach might involve a linear regression model, popular in yield forecasting since it directly evaluates how much a dependent variable like yield may be explained by one or more independent variables - in this case, conditions.

Using corn conditions for week 27 to predict final yield deviation from trend results in an R-square of 0.56, meaning about 56% of the yield variation can be explained by week 27 conditions.

That R-square jumps to 0.69 in week 28 (mid-July) and tops out in weeks 29 and 30 (late July) at 0.73, staying above 0.6 through late September. This suggests corn conditions have max correlation with actual yield deviations in late July, though including other variables such as July or August weather would likely enhance the model's reliability.

The same analysis for soybean yield deviations from trend results in a much worse R-square, which stays below 0.5 until the end of August. Week 27 produces an R-square of 0.30, a poor relationship by itself.

U.S. soybean condition at 51% GE is the fourth-worst week 27 rating since 1986, and yields were poor in those top three years. But the six years with conditions between 52% and 55% GE are curious since they offer three below-trend, two above-trend and one trend-yielding year. Karen Braun is a market analyst for Reuters. Views expressed above are her own.

(Reporting by Karen Braun Editing by Matthew Lewis)