You can open the City of Temecula GIS viewer by clicking this link. (pop up)
Step 1:
Select either checkboxes here in the "Zoning and Land Use" section of the Map Layers box located on the right hand side of the screen. (see below)

Step 2:
GIS allows you to search by assessor parcel number, address, and lot/tract. Click on the search option of your choice.
You can also find the property visually by left-click and dragging creating a box on the map of the general area of your property.

Step 3:
Once your property is located, you will start to see streets, parcels, and color coded zoning regions. The zoning classifications are written by a two letter acronym (see below)

Step 4:
For more detailed mapping you can zoom in further by selecting a smaller part of the map. The icons shown at the top of the page will allow you to manipulate the information needed.

Final Step:
Once a zoning classification is known, you can read the description of the zoning classifications by clicking here. For the example above, the red area is zoned CC:
- Community Commercial (CC) . The community commercial designation includes retail, professional office and service-oriented business activities which serve the entire community. Community commercial areas typically include some neighborhood commercial uses as well as larger retail uses including department stores, theaters, restaurants, professional offices, specialty retail stores and shopping centers.
Same example, the yellow community to the north-west of the commercial is zoned LM:
- Low Medium Density Residential (LM). The low medium density residential zoning district is intended to provide for the development of single-family homes. Typical density for the low medium density residential development is from three to six dwelling units per net acre, with a target density of four and one-half dwelling units per acre.