October 20 in Des Moines
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 Des Moines actually delivers on this date, and how often.
On October 20, Des Moines, IA typically reaches 62°F, but has run anywhere from 48°F to 76°F in eight years out of ten. About 69% of October 20s see no measurable precipitation.
The odds on October 20
Odds computed from the last 30 years (1996–2025).
Where this comes from: 840 daily observations from DES MOINES INTL AP, covering 1970–2025. We pool every day within 7 days of October 20 — a single calendar date has only about 55 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 1970–2025 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 2025 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 Des Moines, IA 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.