July 13 in Chicago
Weather forecasts run out after about two weeks. For any date further out than that, the honest answer isn't a single number — it's the range Chicago actually delivers on this date, and how often.
On July 13, Chicago, IL typically reaches 85°F, but has run anywhere from 76°F to 93°F in eight years out of ten. About 68% of July 13s see no measurable precipitation.
The odds on July 13
Odds computed from the last 30 years (1997–2026).
Highs around July 13 have cooled about 0.2°F per decade since 1970 — roughly 1.2°F across the record. The figures above are shifted along that trend to 2026, so they describe today's climate rather than the average of the last 56 years.
Where this comes from: 854 daily observations from CHICAGO MIDWAY AP 3SW, covering 1970–2026. We pool every day within 7 days of July 13 — a single calendar date has only about 56 readings, far too few to place a 10th percentile you'd want to trust.
Why it's not a plain average: A climatology computed straight across 1970–2026 describes the middle of that period, not today, so as a statement about the present it runs cold. We fit a trend on year and shift each observation to 2026 before taking the range. The probabilities use the last 30 years instead — shifting a temperature along a trend is well defined, shifting “did it rain” is not.
What this is not: Not a forecast. It is what Chicago, IL has actually done on this date, which is the only defensible answer once you're past the two-week horizon where real forecasts stop. Data: NOAA NCEI GHCN-Daily.