What is the best alternative to Barometer & Altimeter & Thermo on iPhone?

Thermometer++ App, A tier, #2 in barometer.

Is there a free alternative to Barometer & Altimeter & Thermo?

Yes: Thermometer++ App (A tier, #2) is free to download.

No. Barometer & Altimeter & Thermo is #1 in barometer.

Barometer & Altimeter & Thermo is S tier, #1 of 6 in barometer. Here is everything that competes with it on iPhone, in tier order.

2
Thermometer++ AppA
Free download · ★ 4.7 · 7,288 ratings · score 83
Shows current outdoor temperature, humidity, pressure, and wind for your location or a location chosen on a map.
3
WeatherX ForecastA
Free · ★ 4.3 · 2,357 ratings · score 83
Shows a 5-day barometric pressure forecast and history with push alerts, meant to be used alongside WeatherX earplugs.
4
Thermo-hygrometerB
$3.99 · ★ 4.7 · 1,914 ratings · score 80
Shows outdoor temperature, feels-like, humidity, pressure and discomfort index for your location on analog-style gauges.
5
Gauges: Speedometer & SensorsB
Free download · ★ 4.6 · 3,079 ratings · score 78
Live gauges for iPhone and iPad measuring speed, altitude, pressure, compass, sound, light and other sensors.
6
eWeather HD - Weather & AlertsC
$3.99 · ★ 4.7 · 8,819 ratings · score 69
Weather app with hourly and 15-day forecasts, radar, lightning tracking, severe alerts, tides and air quality.

What is the best alternative to Barometer & Altimeter & Thermo on iPhone?: Thermometer++ App, A tier, #2 in barometer.
Is there a free alternative to Barometer & Altimeter & Thermo?: Yes: Thermometer++ App (A tier, #2) is free to download.
Does anything rank above Barometer & Altimeter & Thermo?: No. Barometer & Altimeter & Thermo is #1 in barometer.