* WHAT. High temperatures for the inland valleys in the upper 90s to 106 expected. * WHERE. San Diego County Valleys. * WHEN. From 10 AM Tuesday to 8 PM PDT Wednesday. * IMPACTS. Hot temperatures may cause heat illnesses.

* WHAT. Dangerously hot conditions with temperatures from 108 to 114 and low temperatures in the mid 70s to lower 90s expected. * WHERE. Coachella Valley and San Diego County Deserts. * WHEN. From 10 AM Tuesday to 9 PM PDT Thursday. * IMPACTS. Heat related illnesses increase significantly during extreme heat events.

* WHAT. High temperatures from 100 to 108 expected. * WHERE. San Bernardino and Riverside County Valleys-The Inland Empire. * WHEN. From 10 AM Tuesday to 8 PM PDT Wednesday. * IMPACTS. Hot temperatures may cause heat illnesses.

* WHAT. High temperatures from 100 to 108 expected. Low temperatures will be elevated in the upper 60s to low 70s. * WHERE. San Bernardino and Riverside County Valleys-The Inland Empire. * WHEN. From 10 AM Tuesday to 8 PM PDT Thursday. * IMPACTS. Hot temperatures may cause heat illnesses.

* WHAT. Dangerously hot conditions with temperatures from 108 to 114 and low temperatures in the mid 70s to lower 90s expected. * WHERE. Coachella Valley and San Diego County Deserts. * WHEN. From 10 AM Tuesday to 8 PM PDT Thursday. * IMPACTS. Heat related illnesses increase significantly during extreme heat events.

* WHAT. High temperatures for the inland valleys in the upper 90s to 106 expected. Low temperatures will be elevated in the upper 60s to low 70s. * WHERE. San Diego County Valleys. * WHEN. From 10 AM Tuesday to 8 PM PDT Thursday. * IMPACTS. Hot temperatures may cause heat illnesses. * ADDITIONAL DETAILS. Wednesday will be the hottest day, with similar temperatures expected Tuesday and Thursday.

* WHAT. Temperatures in the mid-80s to upper 90s expected. Low temperatures will be elevated in the upper-60s to mid-70s. * WHERE. San Diego County Mountains. * WHEN. From 11 AM Tuesday to 8 PM PDT Thursday. * IMPACTS. Hot temperatures may cause heat illnesses.

Dense fog with visibility of 1 nm or less will be possible tonight through Tuesday morning from the coast out to 60 nautical miles. Be prepared for sudden changes in visibility. Reduce speeds and be on the lookout for exposed rocks and other vessels, including large ships in the shipping lanes. Use radar or GPS navigation if available, and consider remaining in harbor if such equipment is unavailable.

The South Coast AQMD has extended an air quality alert due to increased fine particle pollution from wildfire smoke in the region. The air quality alert is in effect until 5 PM Monday. If you smell smoke or see ash due to a wildfire, remain indoors with windows and doors closed or seek alternative shelter, if feasible. Avoid vigorous physical activity and run your air conditioner and/or an air purifier. If possible, do not use whole house fans or swamp coolers that bring in outside air. Avoid burning wood in your fireplace or firepit and minimize sources of indoor air pollution such as candles, incense, pan-frying, and grilling. If you must be outdoors, keep the time brief and wear a tightly-fitted N-95 or P- 100 respirator to help reduce exposure. Limit the use of gasoline powered lawn and garden equipment. Exposure to particle pollution can cause serious health problems, aggravate lung disease, cause asthma attacks and acute bronchitis, and increase risk of respiratory infections. People with heart or lung diseases should follow their doctor's advice for dealing with episodes of unhealthy air quality. Additionally, people with respiratory or heart disease, older adults, and children are particularly susceptible and should avoid prolonged exposure, strenuous activities or heavy exertion as conditions dictate. Levels of particle pollution can vary hour by hour and by location depending on fire behavior and local weather conditions. To view current and forecasted air quality levels, visit the South Coast Air Quality Management District website at aqmd.gov or download the mobile app at www.aqmd.gov/mobileapp. Additional details for this air quality alert may be available at www.aqmd.gov/advisory. To view current and forecasted air quality levels, visit the Mojave Desert Air Quality Management District website at mdaqmd.ca.gov. Additional details for this air quality alert may be available at www.mdaqmd.ca.gov/advisories.