1. It rains more often.
2. It rains oftener.
3. It rains most often in this area.
4. It rains oftenest in this area.
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Which ones are grammatical? Are all grammatical? Which ones are commonly used?
1 and 3 are grammatical. "Oftenest" is not commonly used. I'm not sure it's a word!
Both statements 1 and 3 are grammatically correct and commonly used.
1. "It rains more often." This sentence compares the frequency of rain between two different time periods, locations, or conditions. For example, it could mean that it rains more often now compared to before, or that it rains more often in one place than another. This comparative form is regularly used in everyday speech and writing.
3. "It rains most often in this area." This statement indicates that among several locations or areas being discussed, this particular area experiences rain more frequently. This superlative form expresses the highest degree of frequency. It is also commonly used.
Statement 2 ("It rains oftener") and statement 4 ("It rains oftenest in this area") are grammatically accurate but less commonly used. These comparative and superlative forms of the adverb "often" are less frequently employed in modern English. Native speakers of English tend to prefer using the phrases "more often" and "most often" for comparative and superlative comparisons of frequency.