By CHRIS COLLINS
(undated) — Today marks the beginning of what meteorologists say will be our latest heat wave in Massachusetts. An Excessive Heat Warning has been issued for all four western counties as hazy, hot and humid weather is expected to overspread the region. Unhealthy air quality is also expected, and people with breathing issues or compromised immune systems should limit outdoor activity, especially during the hotter parts of the day. The hot weather is expected to stick around at least through Friday.