January 5 in San Francisco
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 San Francisco actually delivers on this date, and how often.
On January 5, San Francisco, CA typically reaches 58°F, but has run anywhere from 53°F to 64°F in eight years out of ten. About 63% of January 5s see no measurable precipitation.
The odds on January 5
Odds computed from the last 30 years (1997–2026).
Highs around January 5 have warmed about 0.7°F per decade since 1970 — roughly 3.7°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: 810 daily observations from SAN FRANCISCO DWTN, covering 1970–2026. We pool every day within 7 days of January 5 — 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 San Francisco, CA 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.