Five Seasons Calendar

Five Seasons Calendar is a  proposed Standard Year by Stavros Daliakopoulos, Greece.

The proposal consists of four large periods of 84 days and one small period of 28 days, i.e. 12 weeks and 4 weeks, respectively.

The seven-day week cycle is preserved but there are no more months.

First Period

Mon	Tue	Wed	Thu	Fri	Sat	Sun
01	02	03	04	05	06	07
08	09	10	11	12	13	14
15	16	17	18	19	20	21
22	23	24	25	26	27	28
29	30	31	32	33	34	35
36	37	38	39	40	41	42
43	44	45	46	47	48	49
50	51	52	53	54	55	56
57	58	59	60	61	62	63
64	65	66	67	68	69	70
71	72	73	74	75	76	77
78	79	80	81	82	83	84

Second period

Mon	Tue	Wed	Thu	Fri	Sat	Sun
01	02	03	04	05	06	07
08	09	10	11	12	13	14
15	16	17	18	19	20	21
22	23	24	25	26	27	28
29	30	31	32	33	34	35
36	37	38	39	40	41	42
43	44	45	46	47	48	49
50	51	52	53	54	55	56
57	58	59	60	61	62	63
64	65	66	67	68	69	70
71	72	73	74	75	76	77
78	79	80	81	82	83	84

Third period

Mon	Tue	Wed	Thu	Fri	Sat	Sun
01	02	03	04	05	06	07
08	09	10	11	12	13	14
15	16	17	18	19	20	21
22	23	24	25	26	27	28

Fourth period

Mon	Tue	Wed	Thu	Fri	Sat	Sun
01	02	03	04	05	06	07
08	09	10	11	12	13	14
15	16	17	18	19	20	21
22	23	24	25	26	27	28
29	30	31	32	33	34	35
36	37	38	39	40	41	42
43	44	45	46	47	48	49
50	51	52	53	54	55	56
57	58	59	60	61	62	63
64	65	66	67	68	69	70
71	72	73	74	75	76	77
78	79	80	81	82	83	84

Fifth period

Mon	Tue	Wed	Thu	Fri	Sat	Sun
01	02	03	04	05	06	07
08	09	10	11	12	13	14
15	16	17	18	19	20	21
22	23	24	25	26	27	28
29	30	31	32	33	34	35
36	37	38	39	40	41	42
43	44	45	46	47	48	49
50	51	52	53	54	55	56
57	58	59	60	61	62	63
64	65	66	67	68	69	70
71	72	73	74	75	76	77
78	79	80	81	82	83	84: Double or triple Sunday

To complete the 365-day cycle, the last Sunday of the year will be a "double" Sunday (DS), meaning it will have 48 hours instead of 24, so that the seven-day week is preserved. The same principle will apply for the leap years so we have a "triple" Sunday (TS) every 4 years that has 72 hours instead of 24.

Advantages

• No months to memorize  
• No 13 months as other proposals   
• The first weekday of the week is Monday as per ISO 8601
• No Friday the 13th days (only five 13s in the whole calendar)
• Each large period has 12 weeks
• One small period has 4 weeks
• Symmetrical (half year is 2 large and 1/2 small periods, or 182 days), so statistical comparisons are more accurate  
• Quarterly statistics are also easier (91 days for each quarter although they intercept periods)
• Every day falls on the same weekday in each period (e.g. the 9th always falls on a Tuesday)  
• Each large period can be divided by 2, 3, 4 and 6. The small period can be divided by 2 and 4.
• The calendar is the same every year (perennial), unlike the annual Gregorian calendar, which differs from year to year  
• Scheduling is easier for institutions and industries with extended production cycles.
• Movable holidays would be able to have a fixed date while keeping their traditional weekday.
• The periods could be given historical names.

Disadvantages

• Birthdays, significant anniversaries, and other holidays would need to be recalculated as a result of a calendar reform, and would always be on the same day of the week

• Large day count in periods.

• Does not assign unique dates to the 364th, 365th (and 366th) days of a year.