diff --git a/.env.example b/.env.example
index aa83756..d665c35 100644
--- a/.env.example
+++ b/.env.example
@@ -1,5 +1,7 @@
 CHANNEL_ID=C0XXXYYYZZZ
 CLOSURE_DAY=25
+DEBUG=0
+DEBUG_DATE=
 JOB_HOUR=10
 JOB_MONTH_END=11
 JOB_MONTH_START=2
diff --git a/README.md b/README.md
index 1ecc1ba..7fa127f 100644
--- a/README.md
+++ b/README.md
@@ -51,6 +51,8 @@ The app uses `.env` config which is based on `.env.example`:
 
 - `CHANNEL_ID` – Slack channel ID for messaging
 - `ClOSURE_DAY` – day of month on which the worklog agenda closes (defaults to `25`)
+- `DEBUG` – set `1` to disable sending messages and only output to console (defaults to `0`)
+- `DEBUG_DATE` – when `DEBUG=1` use this to simulate a specific date for test run (defaults to `undefined`)
 - `JOB_HOUR` – hour at which the messaging schedule runs daily (defaults to `10`)
 - `JOB_MONTH_END` – month in which the messaging schedule ends (defaults to `11`)
 - `JOB_MONTH_START` – month in which the messaging schedule starts (defaults to `2`)
diff --git a/src/app.ts b/src/app.ts
index 4288145..f7207c1 100644
--- a/src/app.ts
+++ b/src/app.ts
@@ -4,6 +4,8 @@ import { Range, RecurrenceRule, scheduleJob } from 'node-schedule';
 import { MAX_MONTH } from './constants';
 import {
   CHANNEL_ID,
+  DEBUG,
+  DEBUG_DATE,
   JOB_HOUR,
   JOB_MONTH_END,
   JOB_MONTH_START,
@@ -35,6 +37,12 @@ logger.logInfo(
   JSON.stringify({ CHANNEL_ID, JOB_MONTH_START, JOB_MONTH_END, JOB_HOUR, TZ }),
 );
 
+if (DEBUG) {
+  logger.logInfo('Running in DEBUG mode, not actually sending to Slack.');
+  if (DEBUG_DATE) logger.logInfo(`Using DEBUG_DATE: ${DEBUG_DATE}`);
+  run().catch(logger.logError);
+}
+
 const shutdownGracefully = () => {
   job.cancel();
   process.exit(0);
diff --git a/src/date.ts b/src/date.ts
index 6b9f23e..975af5e 100644
--- a/src/date.ts
+++ b/src/date.ts
@@ -7,9 +7,9 @@ import {
   SUNDAY,
   SUNDAY_DIFF,
 } from './constants';
-import { CLOSURE_DAY } from './environment';
+import { CLOSURE_DAY, DEBUG_DATE } from './environment';
 
-export const now = () => new Date();
+export const now = () => (DEBUG_DATE ? new Date(DEBUG_DATE) : new Date());
 
 export const formatMonth = (date: Date) => date.getMonth() + 1;
 
@@ -30,3 +30,9 @@ export const getFirstNotificationDay = () =>
 
 export const getLastNotificationDay = () =>
   getFinalDay() - LAST_NOTIFICATION_DAYS;
+
+export const isFinalDayAtWeekend = () => {
+  const date = now();
+  date.setDate(CLOSURE_DAY);
+  return [SATURDAY, SUNDAY].includes(date.getDay());
+};
diff --git a/src/environment.ts b/src/environment.ts
index 9f3b3ec..22a1d2a 100644
--- a/src/environment.ts
+++ b/src/environment.ts
@@ -4,6 +4,8 @@ dotenv.config();
 
 export const CHANNEL_ID = process.env.CHANNEL_ID ?? '';
 export const CLOSURE_DAY = Number(process.env.CLOSURE_DAY ?? '25');
+export const DEBUG = process.env.DEBUG === '1';
+export const DEBUG_DATE = DEBUG ? process.env.DEBUG_DATE : undefined;
 export const JOB_HOUR = Number(process.env.JOB_HOUR ?? '10');
 export const JOB_MONTH_END = Number(process.env.JOB_MONTH_END ?? '11');
 export const JOB_MONTH_START = Number(process.env.JOB_MONTH_START ?? '2');
diff --git a/src/messages.ts b/src/messages.ts
index 94b4f6c..f523874 100644
--- a/src/messages.ts
+++ b/src/messages.ts
@@ -4,7 +4,7 @@ import {
   JANUARY,
   LAST_NOTIFICATION_DAYS,
 } from './constants';
-import { formatMonth, getFinalDay, now } from './date';
+import { formatMonth, getFinalDay, isFinalDayAtWeekend, now } from './date';
 import { CLOSURE_DAY } from './environment';
 import { NotificationDay } from './types';
 
@@ -27,8 +27,20 @@ const getPeriod = () => {
   return `${startDay}.${startMonth}. – ${endDay}.${endMonth}. včetně`;
 };
 
-export const createFirstMessage = () =>
-  `Ahoj <!channel> 👋, blíží se nám další uzávěrka fakturačního období, tentokrát *${getPeriod()}*. Začněte si prosím chystat vaše worklogy a mějte vše *${getFinalDay()}. do 12:00* připraveno. Díky moc! 🫶`;
+export const createFirstMessage = () => {
+  const message = [
+    `Ahoj <!channel> 👋, blíží se nám další uzávěrka fakturačního období, tentokrát *${getPeriod()}*.`,
+  ];
+  if (isFinalDayAtWeekend()) {
+    message.push(
+      `Jelikož nám konec období vychází na víkend, musíme vše uzavřít v pátek.`,
+    );
+  }
+  message.push(
+    `Začněte si prosím chystat vaše worklogy a mějte vše *${getFinalDay()}. do 12:00* připraveno. Díky moc! 🫶`,
+  );
+  return message.join(' ');
+};
 
 export const createNotificationMessage = (day: NotificationDay) => {
   const days = day === LAST_NOTIFICATION_DAYS ? 'den' : 'dny';
diff --git a/src/send-message.ts b/src/send-message.ts
index cf3a2c5..6b11c46 100644
--- a/src/send-message.ts
+++ b/src/send-message.ts
@@ -1,8 +1,15 @@
 import { client } from './client';
-import { CHANNEL_ID } from './environment';
+import { CHANNEL_ID, DEBUG } from './environment';
 import { logger } from './logger';
 import { SendMessageProperties } from './types';
 
+const handleSend = async ({ text }: SendMessageProperties) =>
+  client.chat.postMessage({
+    channel: CHANNEL_ID,
+    mrkdwn: true,
+    text,
+  });
+
 const formatError = (error: unknown) => {
   if (error instanceof Error) return error;
   return new Error(String(error));
@@ -10,11 +17,7 @@ const formatError = (error: unknown) => {
 
 export const sendMessage = async ({ text }: SendMessageProperties) => {
   try {
-    await client.chat.postMessage({
-      channel: CHANNEL_ID,
-      mrkdwn: true,
-      text,
-    });
+    if (!DEBUG) await handleSend({ text });
     logger.logSuccess(`SENT: ${text}`);
   } catch (error: unknown) {
     logger.logError(formatError(error));