Reading from boost serial_port reads incorrect data every few readings

Question

I'm placing a string in my stream buffer of the form of "000.3\r\n 000.3\r\n ...". Every few readings I catch a ".3\r\n 000.3\r\n ... Since, I'm only reading from the buffer once per frame those sudden jumps in value become noticeable when drawing to the screen. How should I go about testing for whether the buffer is ready to read? Just check if I have 000 after the decimal point? Or is there a better way for checking for correct data?

Initializing port:

using namespace boost::asio;
serial_port_base::parity PARITY(serial_port_base::parity::none);
serial_port_base::stop_bits STOPBITS(serial_port_base::stop_bits::one);
serial_port_base::flow_control FLOWCONTROL(serial_port_base::flow_control::none);

port->set_option(serial_port_base::baud_rate(57600));
port->set_option(PARITY);
port->set_option(STOPBITS);
port->set_option(serial_port_base::character_size(8));
port->set_option(FLOWCONTROL);

Reading from the port:

float Serial::ReadData()
{
    boost::asio::streambuf buff;
    read_until(*port, buff, "\r\n");
    std::istream is(&buff);

    float f;
    if (is >> f)
    {
        buff.consume(sizeof(buff);
        return f;
    }

    return 0;
}