Short answer. Yes. Rule 113 of the Rules of Court states that an arrest may be made on any day and at any time of the day or night. There are no protected hours: nighttime, weekends and holidays are all lawful times for an arrest, and the rule draws no exceptions.
What the law says
An arrest may be made on any day and at any time of the day or night.
Rule 113, Section 6 — Time of making arrest. Read the full provision →
One sentence, deliberately broad
The rule on the time of making arrest is a single sentence: an arrest may be made on any day and at any time of the day or night. There is no carve-out for Sundays, holidays, dawn raids or the middle of the night. The reason is the nature of the act — an arrest exists to take a person into custody so that he answers for an offence, and a person who could only be arrested during office hours could simply arrange never to be available during them. The clock and the calendar give no shelter.
The misconception this corrects
People often believe a warrant somehow sleeps outside business hours — that an arrest made at 2 a.m., or while the courts are closed for a holiday, is irregular for that reason alone. It is not. The hour of an arrest, by itself, says nothing about its validity. Some of the confusion comes from mixing arrest up with the service of search warrants, which is governed by its own distinct provisions; the two are different instruments, and the timing rule quoted above is the one that governs arrests.
What still has to be lawful
The rule settles timing and only timing. An arrest at any hour must still rest on a lawful basis — a valid warrant of arrest, or one of the situations in which the Rules allow arrest without a warrant. The person arrested also keeps every right the Constitution guarantees, including the right to be informed of the reason for the arrest, to remain silent and to have counsel. A midnight arrest with no valid basis is unlawful because it lacks a basis, not because of the hour; a properly grounded arrest is lawful at any hour.
If it happened to someone you know
When a relative is taken at an odd hour, the useful questions are not about the time. Ask instead: was there a warrant, and for what case? If there was none, what circumstance is invoked to justify a warrantless arrest? Where was the person brought, and has he been able to speak to a lawyer? The answers to those questions — not the fact that it was a weekend or the middle of the night — determine whether the arrest can be challenged, and they are exactly what counsel will need first.