My house numbers do not show up well at night since they are small and

There isn't much you can do about the size other than to put up new numbers. However you can address the visibility at night by hanging a small solar light close to them.

As a retired Mail Carrier... I can tell you that the larger the number ... the better... and they should be placed as close to the front door as possible... or directly on the front gate, or porch post nearest the front walkway.

Over the years I had several customers, whose house was 100 feet from the street, and they had 1 inch house numbers (if I cannot read it from the street... it doesn't count) or numbers placed on the end of the house opposite from the door (often behind a bush)... and wondered why no one could identify the house.

If you have a dark colored house... paint the numbers white... if you have a white house paint the numbers black...and make sure to repaint the numbers once they start to match the background.. and use at least 4 inch numbers... WE have the ceramic number tiles that are 6 inches tall and we placed them directly under the porch where the light shines on them at night.... Also... most home improvement stores carry Solar house number fixtures that can be place where they are quite visible

How about painting them with reflective paint until you can come up with a better solution? Here are some great house number ideas.

http://www.diynetwork.com/how-to/outdoors/hardscape/house-number-design-ideas-and-projects-pictures

http://diyjoy.com/diy-house-numbers

https://www.pinterest.com/explore/diy-house-numbers/

I bought the sign below, which is reflective and a shepherd's hook. Wrapped a thin wire securely around it (it's got a groove in the edging) and attached it to a stiff chain. It held up through Hurricane Harvey, so it may work for you.

I'm sure any Emergency Response Worker will agree that having clearly visible house numbers after dark is very important to ensure that help reaches you as quickly as possible.

If your present house numbers are insufficient to be read at night, then perhaps you may want to consider mounting an additional set under the beams of an exterior light fixture that can be kept on at night.

Paint the numbers with reflective or glo-in-the-dark paint.

I agree. Paint the numbers with glow in the dark paint. Put a flood light on them. You can make a sign displaying your address with a large font. Hang it where it can be seen from your street. If you have a mail box in front of your house, stencil or paint your address on it.

I purchased a metal address plate with large (about 6 inch) numbers, and hung it directly beneath my porch light.

Also, google "Lighted house numbers"--I found a number of companies, including Amazon, selling a variety of address signs, some with solar lights.

A friend has a house set far back from the road, and they purchased one of these lighted solar signs to place near their driveway entrance.