Lower West Side sexual assault rose 109% against its multi-year baseline, the sharpest single-category move in Chicago this briefing. The signal is not isolated: West Pullman and Douglas both registered the same category in the top five, making sexual assault the dominant story across three distinct neighborhoods this month. No demoted lead is carrying over from prior months, so this is the fresh headline without a recurring backdrop to account for.
Citywide volume is down 5.6% against the prior 12 months, 128,283 incidents against 135,839. That broad decline holds even as 9 fresh spikes registered across the city, concentrated in the top-ranked categories. Gage Park other-larceny and Beverly aggravated assault also moved above their baselines, adding two distinct categories to the month's upward signals alongside the sexual assault pattern.
With 57 sustained-shift signals and 38 below-trend signals against 9 spikes, the structural picture for Chicago remains a city in gradual volume decline. The sexual assault concentration across Lower West Side, West Pullman, and Douglas is new this month and carries no prior-month streak, so October's briefing will be the first test of whether this is a one-month move or the start of a sustained shift.
Sustained drops worth naming
Robbery ran below trend in the trailing 12 months — 32% down from the year before. Sustained shifts often precede a baseline reset; we surface them at the same prominence as spikes.
How last month's forecasts performed
Forecasts for August were issued from data through July 2026. 7 of 9 citywide bucket forecasts (78%) landed inside their 95% prediction intervals.
| Category | Predicted | Actual | Error | In CI |
|---|---|---|---|---|
| Aggravated Assault | 1186[1063–1310] | 1077 | 10.1% | INSIDE |
| Arson | 38[21–56] | 33 | 15.6% | INSIDE |
| Burglary | 620[424–802] | 517 | 19.8% | INSIDE |
| Homicide | 44[26–63] | 36 | 22.8% | INSIDE |
| Motor Vehicle Theft | 2034[1121–2880] | 1475 | 37.9% | INSIDE |
| Other Larceny | 5979[4777–7049] | 4762 | 25.6% | MISS |
| Robbery | 528[316–735] | 501 | 5.3% | INSIDE |
| Sexual Assault | 286[255–319] | 246 | 16.2% | MISS |
| Vandalism | 2384[2135–2612] | 2244 | 6.2% | INSIDE |
Per-bucket coverage, MAPE, and bias across the full 12-month horizon live on the methodology page.
Public Analyst.ai, “August 2026 — Chicago,” archived snapshot.Permanent URL: /chicago/2026/august