Blue Moon 2026
The next Blue Moon rises on Sunday, May 31, 2026, only the third since 2021. Drawing on Nexar's May 2025 fleet baseline and peer-reviewed traffic-safety literature, this study models a "watch-for" narrative, a ceiling scenario consistent with external research, not a verified forecast.
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A signal below the noise.
On May 31, 2026, a Blue Moon will rise over the United States, the second full moon in May 2026 and only the third Blue Moon since 2021. The prior Sunday baseline from Nexar's May 2025 fleet data shows approximately 210,580 rides on a normal non-holiday Sunday, with a baseline collision-proxy rate of 930 high-G impact events per million rides.
Headline scenario, not a prediction. Applying the most defensible estimate from the literature, Tanaka et al. (2018) nationwide RR of 1.042, yields a ceiling of approximately 219,424 rides and a collision-proxy rate of ~969 per million on May 31. The absolute increase of +39 events per million falls below the observed week-to-week variance of ±75 per million, a signal below noise.
This Blue Moon is not a supermoon, it occurs near lunar apogee, making it smaller and dimmer than average. The dramatic +32% motorcycle crash spike documented in the Princeton/JAMA supermoon literature does not apply here. The relevant scenario is the modest 4-5% general-full-moon effect, if real, driven primarily by light effects and potential behavioral distraction, not anything mystical. The professional-fleet context (95% Taxi/Rideshare) may further attenuate behavioral effects documented in studies of general-population drivers.
The full numeric snapshot.
Three baselines (non-holiday Sundays, Memorial Day Sunday, day-count to event) and three scenario points (rides, rate, % vs holiday). The two baselines (200,338 holiday Sunday and 210,580 non-holiday Sunday) bracket the study's reference range; the scenario ceiling (969/M, +9.53% vs Memorial Day) is what the Japanese literature predicts as a maximum plausible effect.
| Metric | Value | Note |
|---|---|---|
| Memorial Day Sunday rides | 200,338 | May 25, 2025 · holiday-suppressed |
| Normal Sunday avg | 210,580 | Non-holiday avg · σ ±4,401 |
| Baseline collision rate | 930 /M | High-G impacts per million rides |
| Blue Moon scenario ceiling | ~969 /M | +4.2% · +39/M · literature ceiling |
| vs Memorial Day Sunday | +9.53% | Scenario vs holiday-suppressed |
| Days until the Blue Moon | 12 | Last Blue Moon Aug 30, 2023 |
The May 31, 2026 Blue Moon occurs near lunar apogee, the farthest point in the Moon's orbit, making it smaller and dimmer than an average full moon. This is the inverse of a supermoon. The +32% motorcycle crash spike found in the Princeton/JAMA supermoon literature explicitly does not apply here.
Once in a blue moon, next on May 31, 2026.
A Blue Moon is the second full moon to occur within a single calendar month. Because a lunar cycle is approximately 29.5 days, most months contain only one full moon. Roughly every 2.5 years, a month is long enough, and the timing favorable enough, to fit two full moons. That rare second occurrence is the Blue Moon. Despite the name, the Moon does not actually appear blue (barring unusual atmospheric conditions from wildfires or volcanic ash).
| Item | Detail |
|---|---|
| Last Blue Moon | August 30, 2023 |
| Next Blue Moon | May 31, 2026 |
| Following Blue Moon | ~2028 - 2029 |
| Frequency | ~ every 2.5 years |
| Lunar cycle length | ~ 29.5 days |
| Calendar month length | 28 - 31 days |
| Common name | "Once in a blue moon" |
Apparent Diameter vs Average Full Moon
The May 31, 2026 Blue Moon occurs near lunar apogee, the Moon's farthest orbital point from Earth. The Moon will appear roughly 12-14% smaller in angular diameter and visibly dimmer than a supermoon. Expect reduced night-visibility enhancement compared to a perigee full moon. The light-driven mechanism behind any traffic effect is correspondingly weakened.
Light, not mysticism.
The Blue Moon occupies a unique place in world mythology, folklore, and modern spiritual practice. Understanding these associations is relevant because behavioral effects, if any exist, are likely mediated through human perception, not lunar physics.
The "lunacy" association persists despite a null literature because of confirmation bias: unusual events on full moon nights are remembered; full moons on quiet nights are not. Any genuine behavioral lift would have to push through this strong cognitive prior to register as a real signal, which is part of why the sub-noise effect modeled here is so hard to detect.
Six studies, wide heterogeneity.
Six peer-reviewed studies are relevant. Effect sizes vary significantly by crash type, region, and study design. The table summarises the most-cited with direct applicability notes.
| Study | Year | Effect Class | Effect Size | Applicability |
|---|---|---|---|---|
| Japanese Nationwide ★ | 2018 | Full moon vs other (emergency transport) | RR 1.042 (+4.2%) | Primary estimate |
| Princeton / JAMA | 2017 | Full moon · fatal motorcycle (US) | +5.3% | Secondary reference |
| Princeton / JAMA · Supermoon | 2017 | Supermoon vs ordinary | +32% | Not applicable |
| MAPFRE Insurance | 2022 | Day after full moon (Spain claims) | +2% | Day-after (June 1, 2026) |
| Saskatchewan (Lavery & Ramsay) ★ | 1998 | Property damage / non-fatal crashes | No effect | Most directly comparable |
| Texas Wildlife-Vehicle | 2024 | Full moon · wildlife (rural TX) | +46% | Context only · rural specific |
The six studies span different countries, crash types, road types, time periods, and methodologies. A +46% effect for rural Texas wildlife collisions does not generalise to urban rideshare vehicles. The Saskatchewan null result for non-fatal crashes is arguably the most directly comparable to Nexar's High-G Impact event class. The +4.2% Japanese estimate is used here as the defensible ceiling for the main scenario, not because it is certain, but because it is the most methodologically robust nationwide study.
Methodology & data sources.
Data source. All baseline metrics are derived from Nexar telematics data for the four Sundays of May 2025. Nexar operates a professional fleet intelligence platform covering primarily Taxi and Rideshare vehicles in the United States. The dataset covers ride-level records including duration, distance, vehicle-type classification, state, and onboard sensor events (high-G impacts, hard braking events).
Baseline construction. The non-holiday rolling average uses Sundays May 4, 11, 18, 2025 (mean 210,580 rides, std deviation ±4,401), a clean statistical reference. The Memorial Day Sunday (May 25, 2025, 200,338 rides, −4.86