For completeness sake, here is the HW Beta 2.0 format. As you can see the data set is not complete. There is for example no relative pressure. That would have to be determined by either reading the relative pressure from the console or by prompting the user for an offset from the abolute pressure.

Source: http://www.niftythings.org/HeavyWeather%20History%20Format.txt

 

HeavyWeather V2.0 beta La Crosse WS-2310 and WS-2315 weather stations

Row Format

Each row of data is stored in 36 byte chunks starting from the beginning of the file (no header).

 

Offset Type Name Unit
00 ULong [4] unknown (Value is always 1)
04 ULong [4] Timestamp seconds from 1/1/1900 00:00:00 (GMT)
08 Float [4] Abs Pressure hectopascals (millibars)
12 Float [4] Wind Speed meters/second
16 ULong [4] Wind Direction see below
20 Float [4] Total Rainfall millimeters
24 Float [4] Indoor Temp Celsius
28 Float [4] Outdoor Temp Celsius
32 UWord [2] Indoor Humidity %
34 UWord [2] Outdoor Humidity %

Trailer

At the end of the file is an additional 28 bytes providing information about the dataset as a whole.

Offset Type Description
00 ULong [4] unknown
04 Ulong [4] unknown (0)
08 Float [4] unknown (5.698)
12 ULong [4] unknown (0)
16 ULong [4] Number of rows
20 ULong [4] Timestamp of the first row of data
24 ULong [4] Timestamp of the last row of data

Wind Direction

Wind direction is encoded as an integer between 0 and 15. To get the wind direction in degrees, multiply the value by 22.5. To get compass directions (moving clockwise) 0 is North, 1 is North-Northeast, 2 is Northeast, etc…

Value Direction
0 N
1 NNE
2 NE
3 ENE
4 E
5 ESE
6 SE
7 SSE
8 S
9 SSW
10 SW
11 WSW
12 W
13 WNW
14 NW
15 NNW