For one concise forecast-versus-detection workflow, start with the lightning forecast near me guide. It keeps local NWS forecasts and SPC outlooks separate from recent map detections.
Three Sources to Answer "Is It Gonna Thunder Today?"
- NOAA Storm Prediction Center day-1 outlook — categorical severe-storm risk (Marginal → Slight → Enhanced → Moderate → High) for the next 24 hours. spc.noaa.gov.
- Local NWS forecast — chance of thunderstorms expressed as a percentage by 12-hour period. forecast.weather.gov.
- Live lightning map — confirms whether storms have actually materialised. Browse our state and city lightning maps.
How to Read the SPC Day-1 Outlook
| Category | Meaning |
|---|---|
| Marginal (MRGL) | Isolated severe storms possible, limited duration / coverage. |
| Slight (SLGT) | Scattered severe storms expected, short-lived, not widespread. |
| Enhanced (ENH) | Numerous severe storms possible, more persistent or intense. |
| Moderate (MDT) | Widespread severe storms likely, including significant tornadoes / hail / wind. |
| High (HIGH) | Severe-weather outbreak expected; long-lived, widespread, intense. |
Most storm days are MRGL or SLGT. ENH+ days are uncommon but high-impact. HIGH-risk days are rare (a few per year nationally) and worth taking seriously.
Reading "Chance of Thunderstorms" Numbers
Local NWS forecasts express thunderstorm probability as a percentage. The number means: of 100 historical days with similar atmospheric conditions, on how many did measurable thunder occur somewhere in the forecast zone.
- 0–20% — storms unlikely; carry-on with outdoor plans but stay aware of changing conditions.
- 30–50% — storms possible; have a shelter plan and monitor the sky / radar.
- 60–80% — storms expected; postpone vulnerable outdoor activities or be ready to take shelter quickly.
- 90%+ — storms near-certain; assume you will be affected, plan accordingly.
Combine Forecast + Live Map for Best Decisions
A 60% chance of thunderstorms tells you the day is risky. A live lightning map tells you whether the risk is materialising right now. Combine both:
- High forecast + active map = stay sheltered, expect lightning. Use the alerts setup guide to get push notifications when strikes hit your radius.
- High forecast + quiet map = storms haven't fired yet but conditions are right. Watch over the next 1–3 hours.
- Low forecast + active map = mesoscale convection caught the forecast off-guard (common with afternoon Florida sea-breeze cells and Gulf Coast outflow). Trust the map; the forecast is stale.
- Low forecast + quiet map = today is genuinely a low risk day. Outdoor plans are fine.
By Region: When Today Likely Has Thunder
- Florida + Gulf Coast — sea-breeze convergence makes summer afternoons (June–September) almost daily storm days.
- Great Plains (TX, OK, KS, NE) — dry-line storms April–June produce the most violent supercell days.
- Midwest (IA, MO) — frontal storms May–August.
- Mountain West (CO, AZ, NM) — afternoon monsoon storms July–September.
- Northeast / Pacific Coast — fewer storm days; check forecast on case-by-case basis.