Thor Guard alternative: Flash vs Thor Guard, two ways to warn before the first strike

The short answer

Thor Guard’s TG360 is an on-site system. A rooftop sensor samples the atmospheric electric field and uses Thor Guard’s algorithms to warn before a first strike near the sensor; it also detects lightning on site, includes a weather station and drives its own horns and strobes. Flash is software. It forecasts, for every 1×1 km cell, the likelihood of a cloud-to-ground strike in the next 60 minutes, refreshed every 2 minutes, with up to 99.6% one-hour accuracy scored against NLDN strikes. Choose Thor Guard if you want a self-contained system at one property that keeps working without internet. Choose Flash if you want early warning across one site or hundreds without installing anything.

What Thor Guard does well

Everything in this section is as published on thorguard.com, checked 15 Oct 2026.

• Long experience. Thor Guard has built lightning prediction systems since 1973 and says its first complete warning system went to professional golf tours in the 1990s.
• Warning before the first strike. The TG360 measures static electricity in the atmosphere and tracks how that energy builds and changes, aiming to warn before a first strike in a defined area near the sensor.
• On-site detection as well. The same sensor detects lightning on site, with integrated photocells and an electrostatic sampling rate Thor Guard puts at more than 170,000 samples per second.
• Independence from the internet. Thor Guard says the TG360 keeps working if power or the internet goes down, and that its system does not rely on internet connectivity to operate.
• Weather and heat on site. Each TG360 ships with a Davis Vantage Pro 2 weather station for rainfall, evapotranspiration, wind, temperature and humidity, used to calculate heat warnings.
• A full alerting stack. Voice of Thor horns and strobes communicate by radio from a base unit to as many remote receivers as you need, with ThorTV and ThorMobile displays and the ThorAlert app for lightning, heat, wind and emergency notifications.
• Warranty. Thor Guard lists a three-year TG360 assembly warranty and lifetime software upgrades.

Thor Guard lists sports facilities, schools, parks, municipalities and event organisers among the organisations it serves, and its site carries testimonials from golf clubs and a school.

How Flash approaches the same problem

An electrostatic sensor reads the field at the point where it is mounted. That is a real physical measurement, and it can rise before a strike. It also means the warning describes the area around that sensor, and every property you want covered needs its own sensor, mounting and upkeep. Flash forecasts from the other direction: it ingests 30+ integrated data signals, including radar, satellite and surface observations, and outputs a likelihood of a cloud-to-ground strike over the next 60 minutes for every 1×1 km cell across the continental U.S., refreshed every 2 minutes.

• 60 minlead time, up to
• 1×1 kmcell per site
• 2 minmodel refresh
• Up to 99.6%one-hour lightning accuracy

Because a forecast can be wrong, Flash scores it like one: hit or miss per cell on the one-hour window, against an independent record of NLDN strikes. The definitions, including first-strike detection and false-alarm ratio, are on the accuracy method page. Thor Guard’s FAQ describes its accuracy as high, with detection and prediction up to 100 miles away; we did not find a published accuracy percentage or scoring method on the pages we checked, so ask for one.

Flash runs in the web app, the mobile app, SMS and email, and drives horns and strobes you already own through relays. Where you want a new siren that sounds on the forecast, Flash Weather Shield is solar-powered and cellular. For heat, a 6-hour WBGT outlook plans alongside any on-site reading your policy requires.

Thor Guard vs Flash, side by side

• Thor Guard TG360

  How it warns early

  Rooftop sensor reads the atmospheric electric field near the site

  Coverage

  A defined area around each installed sensor

  Accuracy

  Described as high; no percentage or method found on the pages we checked

  Without internet

  Says it keeps working if power or the internet goes down

  Hardware

  Sensor, weather station, server laptop, radio horns and strobes

  Heat

  On-site weather station used for heat warnings

  Pricing

  Not published; inquire through thorguard.com

• Flash

  How it warns early

  Model forecasts strike likelihood per 1×1 km cell from 30+ data signals

  Coverage

  Any site in the continental U.S., each on its own 1×1 km cell

  Accuracy

  Up to 99.6% one-hour accuracy against NLDN strikes; method published

  Without internet

  Software with no on-site unit: web app, mobile app, SMS and email

  Hardware

  None required; relays for existing horns, or Flash Weather Shield

  Heat

  6-hour WBGT outlook beside any on-site reading

  Pricing

  Per site, annual, quoted after a demo; free app tier for individuals

When Thor Guard is the better fit

• You want a warning system that does not depend on an internet connection at a single, well-defined property.
• You want an on-site weather station, lightning sensor and radio horns from one manufacturer.
• Your staff already know and trust the Thor Guard colour system and display.

When Flash is the better fit

• You cover many sites, such as a district, a park system or a portfolio of courses, and do not want a sensor, mast and maintenance plan at each one.
• You want every field, pool or hole judged on its own 1×1 km cell, not on one sensor’s surroundings.
• You want a published, checkable accuracy method behind the alert.

Flash is a Preferred Vendor Partner across all 700+ Troon golf properties, the official weather safety provider of the Big 12 Conference, and the Official Weather Monitoring & Alert System of the NAIA through October 2028.

Running both

An on-site sensor and a gridded forecast measure different things, and they can back each other up. Sites with a Thor Guard system can add Flash for the wider picture: the next hour on every cell around the property, on the phones of the people making the call. The prediction vs sensors vs detection explainer compares the three technologies in more depth.

• Everyone else vs Flash  →
• Read the accuracy method  →
• Golf  →

Frequently asked