How Important Are The Temperature Limitations On Sealer Application?

Very important!

Even though the thermometer says 85 degrees, the surface to be sealed can be 20 or more degrees higher. All sealers will tend to dry faster than designed if applied to a hot surface. That could mean insufficient time to properly penetrate (and/or spread to a tough film) and bond.

If the surface temperature is too cold, the normal flowing and curing characteristics are also changed from what was designed into the formulas. The differences could also negatively effect penetrating and/or spreading.

Also, a water based sealer allowed to freeze can experience separation of the components. Thawing and remixing might not be sufficient to reblend.

Solvent base products are generally more tolerant of the effects of colder weather applications. Test first.

We build into the formulas the greatest possible variations from ideal conditions, but please don't assume any risk that is avoidable.

How Important Are The Humidity Limitations On Sealer Application?

It is not the humidity in the air that is the issue, but the moisture in the tile or stone.  Humid air will only slow down the drying/curing somewhat, but the sealer will reach its normal hardness.  However, do a small test patch to make sure there are no surprises.

The water content of the surfacing itself can make a difference. See the sealer label for its moisture tolorance. If the surfacing is damp and will never dry out enough to give you a dry application, test:

Note:
Sometimes, despite your diligent research and the best of intentions of your suppliers salesperson, you might have been given the wrong information. Therefore, no matter how confident you are, whether first time user or seasoned professional, it just makes good sense to patch test a small area and evaluate the results in a few hours before doing a large area.

Most Aldon sealers have more than one area they can be used in any project. Check sealer information on the web site.