Bosch has stepped up their game with their new BMP280 sensor, an environmental sensor with temperature, barometric pressure that is the next generation upgrade to the BMP085 / BMP180 / BMP183. This sensor is great for all sorts of weather sensing and can even be used in both I2C and SPI! This precision sensor from Bosch is the best low-cost, precision sensing solution for measuring barometric pressure with 1 hPa absolute accuraccy, and temperature with 1.0 C accuracy. Because pressure changes with altitude, and the pressure measurements are so good, you can also use it as an altimeter with 1 meter accuracy