SAN DIEGO (FOX 5/KUSI) — Spring heat has arrived in San Diego with 80 degree weather in store this week for parts of the county under a ridge of high pressure. Monday will be the warmest day for the coast and inland valleys while the mountains and deserts will continue to heat up into Tuesday. West of the mountains, afternoon temperatures will range from 10 to 20 degrees above normal for this time of year.  Some hazy conditions will stretch across the coastline, but otherwise mostly clear skies from the coast to the cacti can be expected. Low clouds will return for coastal areas later Monday evening into the early morning hours on Tuesday. More weather: ➡️ Forecast | ⚠️ Alerts | 🗺️ Live Radar | 📧Newsletter The marine layer will remain somewhat shallow, and any low clouds or fog will likely be isolated to the coast.  Tuesday's afternoon temperatures will top out in the low 70s for the coast, low 80s for the valleys, mid 70s for the mountains and mid-90s for the deserts.  Temperatures will cool midweek as the ridge of high pressure shifts east to make room for an upper-level trough to our northwest. The second half of the week will mostly be dominated by this trough pattern, which is expected to bring cooler and cloudier weather. That said, precipitation is unlikely heading into the weekend.  ...read more read less