Saint-Agapit
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Saint-Agapit clear sky chart from 2005-11-06 to 2025-07-21.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	19% 11% 4 9% 5% 4 4 4 5% 6% 29%	119649
	Night	18% 13% 4 10% 5% 5% 4 3 5% 5% 27%	119504
Transparency	Day	54% 7% 13% 17% 8% 1	123149
	Night	57% 6% 12% 17% 8% 1	124166
Seeing	Day	25% 16% 29% 20% 8% 2	16026
	Night	25% 13% 30% 25% 7%	24587

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	17% 22% 6% 14% 5% 4 4 3 4 3 19%	3597
	11th to 20th	Day	10% 17% 8% 18% 8% 5% 4 3 3 3 20%	3570
	21st to end	Day	8% 13% 7% 13% 7% 6% 5% 4 5% 6% 27%	3960
February	1st to 10th	Day	12% 16% 6% 14% 8% 4 4 3 4 4 23%	1603
	11th to 20th	Day	14% 18% 6% 12% 6% 6% 5% 3 4 5% 22%	1947
	21st to end	Day	12% 16% 6% 11% 6% 4 4 3 4 6% 27%	1650
March	1st to 10th	Day	19% 17% 6% 11% 5% 4 4 3 4 4 23%	4476
	11th to 20th	Day	15% 16% 5% 9% 5% 4 4 4 4 5% 29%	4741
	21st to end	Day	20% 13% 4 8% 4 3 4 3 4 4 32%	5827
April	1st to 10th	Day	23% 13% 4 9% 5% 4 4 3 4 5% 28%	2400
	11th to 20th	Day	20% 11% 3 7% 4 3 4 3 4 6% 35%	2459
	21st to end	Day	23% 11% 3 8% 4 4 4 3 4 5% 30%	2600
May	1st to 10th	Day	28% 9% 3 7% 4 4 4 3 5% 6% 27%	6019
	11th to 20th	Day	20% 7% 3 7% 5% 5% 5% 4 6% 7% 29%	6318
	21st to end	Day	19% 8% 3 8% 5% 5% 5% 4 6% 6% 29%	6949
June	1st to 10th	Day	20% 7% 3 7% 5% 6% 6% 4 6% 7% 28%	2973
	11th to 20th	Day	19% 6% 2 6% 4 4 4 4 6% 8% 35%	3000
	21st to end	Day	24% 8% 3 8% 5% 4 4 4 5% 7% 28%	2978
July	1st to 10th	Day	14% 8% 3 8% 6% 6% 5% 4 6% 8% 31%	4580
	11th to 20th	Day	15% 7% 3 8% 5% 5% 5% 6% 7% 9% 31%	4580
	21st to end	Day	14% 7% 3 5% 4 4 5% 4 6% 7% 41%	4814
August	1st to 10th	Day	17% 7% 3 7% 5% 5% 6% 5% 7% 10% 28%	4399
	11th to 20th	Day	20% 7% 3 7% 5% 5% 5% 4 6% 8% 29%	4045
	21st to end	Day	21% 7% 2 6% 4 4 4 3 5% 6% 38%	4312
September	1st to 10th	Day	17% 5% 2 7% 5% 4 4 4 6% 8% 38%	2280
	11th to 20th	Day	17% 7% 2 6% 3 3 3 3 5% 7% 45%	2115
	21st to end	Day	19% 8% 3 6% 4 4 4 3 5% 6% 38%	2090
October	1st to 10th	Day	21% 8% 3 7% 5% 4 4 4 5% 7% 31%	2082
	11th to 20th	Day	21% 11% 4 9% 6% 4 5% 5% 5% 5% 26%	1748
	21st to end	Day	27% 14% 3 7% 5% 4 4 3 4 5% 24%	1881
November	1st to 10th	Day	20% 12% 3 8% 6% 5% 4 3 4 5% 31%	1761
	11th to 20th	Day	21% 15% 4 10% 6% 3 4 3 4 5% 25%	1800
	21st to end	Day	23% 19% 5% 8% 5% 4 4 3 4 4 22%	1484
December	1st to 10th	Day	19% 16% 6% 12% 5% 5% 4 3 5% 5% 20%	2280
	11th to 20th	Day	20% 16% 5% 11% 5% 5% 3 3 3 4 25%	2618
	21st to end	Day	22% 16% 4 10% 5% 4 5% 4 5% 5% 21%	3713
January	1st to 10th	Night	17% 21% 7% 13% 6% 4 4 3 4 4 19%	6349
	11th to 20th	Night	10% 21% 8% 18% 7% 5% 5% 3 4 3 15%	6315
	21st to end	Night	9% 13% 6% 13% 7% 7% 5% 4 5% 6% 26%	6996
February	1st to 10th	Night	13% 15% 6% 12% 9% 5% 5% 4 4 5% 23%	2795
	11th to 20th	Night	13% 17% 5% 13% 7% 6% 3 3 4 4 23%	2338
	21st to end	Night	15% 17% 5% 9% 6% 4 4 3 5% 5% 28%	1980
March	1st to 10th	Night	21% 15% 4 10% 5% 4 5% 2 4 4 25%	5364
	11th to 20th	Night	16% 14% 4 9% 6% 5% 5% 4 5% 6% 24%	5217
	21st to end	Night	19% 16% 4 9% 5% 4 3 3 4 4 29%	5102
April	1st to 10th	Night	22% 13% 5% 8% 4 3 4 3 5% 6% 28%	2000
	11th to 20th	Night	21% 11% 3 7% 5% 4 4 4 4 6% 31%	1889
	21st to end	Night	25% 10% 3 7% 5% 3 2 3 4 5% 33%	1800
May	1st to 10th	Night	24% 9% 4 9% 5% 5% 5% 3 5% 5% 26%	3963
	11th to 20th	Night	25% 8% 3 7% 5% 4 4 3 4 6% 30%	3575
	21st to end	Night	19% 8% 3 7% 4 5% 4 3 6% 7% 34%	3926
June	1st to 10th	Night	22% 9% 3 5% 5% 4 4 4 6% 7% 30%	1423
	11th to 20th	Night	18% 7% 3 7% 5% 4 5% 4 6% 7% 34%	1400
	21st to end	Night	21% 8% 2 8% 7% 4 5% 4 5% 6% 30%	1416
July	1st to 10th	Night	13% 8% 3 8% 6% 6% 5% 4 7% 8% 31%	2600
	11th to 20th	Night	19% 7% 2 6% 5% 4 4 4 5% 7% 35%	2600
	21st to end	Night	13% 6% 3 7% 5% 5% 5% 4 6% 7% 39%	2739
August	1st to 10th	Night	19% 8% 3 7% 5% 5% 4 4 6% 8% 31%	2506
	11th to 20th	Night	17% 8% 3 8% 6% 6% 6% 5% 5% 8% 30%	2775
	21st to end	Night	19% 6% 3 7% 5% 5% 4 3 5% 6% 37%	3341
September	1st to 10th	Night	18% 6% 3 7% 4 4 3 3 5% 7% 40%	1900
	11th to 20th	Night	16% 7% 2 6% 3 3 3 3 4 6% 46%	2064
	21st to end	Night	18% 7% 2 6% 5% 4 4 3 5% 7% 41%	2090
October	1st to 10th	Night	18% 9% 3 7% 4 4 5% 4 5% 5% 37%	2095
	11th to 20th	Night	24% 9% 3 8% 5% 5% 4 3 5% 5% 31%	2432
	21st to end	Night	25% 12% 3 8% 4 4 3 3 5% 5% 28%	2717
November	1st to 10th	Night	19% 13% 4 9% 5% 4 4 3 4 7% 29%	2537
	11th to 20th	Night	19% 13% 5% 9% 5% 4 4 3 4 5% 30%	2600
	21st to end	Night	21% 19% 5% 10% 5% 4 3 3 3 5% 22%	2910
December	1st to 10th	Night	18% 16% 7% 14% 7% 6% 5% 4 4 4 16%	4910
	11th to 20th	Night	21% 17% 5% 11% 6% 4 4 3 4 4 22%	5591
	21st to end	Night	21% 18% 5% 8% 4 4 4 3 4 4 24%	7249

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	70% 5% 9% 12% 5%	3598
	11th to 20th	Day	67% 7% 7% 13% 4 1	3600
	21st to end	Day	55% 8% 9% 16% 12%	3960
February	1st to 10th	Day	65% 4 9% 13% 7% 2	1603
	11th to 20th	Day	65% 5% 11% 12% 6% 1	1956
	21st to end	Day	58% 5% 11% 17% 8% 2	1650
March	1st to 10th	Day	62% 6% 9% 12% 9% 3	4479
	11th to 20th	Day	56% 6% 15% 14% 8%	4741
	21st to end	Day	55% 4 8% 16% 14% 3	5827
April	1st to 10th	Day	60% 4 10% 14% 10% 3	2400
	11th to 20th	Day	51% 5% 10% 21% 11% 2	2459
	21st to end	Day	57% 5% 9% 16% 11% 2	2600
May	1st to 10th	Day	57% 6% 10% 17% 10% 1	6030
	11th to 20th	Day	50% 10% 15% 15% 7% 2	6322
	21st to end	Day	52% 8% 12% 15% 11% 2	6949
June	1st to 10th	Day	52% 9% 11% 19% 7% 1	2973
	11th to 20th	Day	45% 8% 15% 20% 11% 1	3000
	21st to end	Day	56% 7% 11% 16% 9%	2978
July	1st to 10th	Day	47% 8% 16% 23% 6%	4510
	11th to 20th	Day	45% 10% 19% 21% 4	4505
	21st to end	Day	40% 8% 17% 27% 8%	4661
August	1st to 10th	Day	47% 11% 19% 19% 4	4385
	11th to 20th	Day	49% 10% 19% 16% 5%	4084
	21st to end	Day	46% 7% 14% 20% 12% 1	4312
September	1st to 10th	Day	43% 7% 15% 24% 9% 1	2280
	11th to 20th	Day	39% 5% 16% 28% 11%	2115
	21st to end	Day	47% 6% 14% 25% 9%	2090
October	1st to 10th	Day	53% 7% 14% 22% 4	3459
	11th to 20th	Day	53% 6% 18% 20% 2	2886
	21st to end	Day	55% 6% 15% 17% 6%	3081
November	1st to 10th	Day	56% 6% 12% 18% 7%	1761
	11th to 20th	Day	62% 5% 10% 16% 7%	1800
	21st to end	Day	67% 5% 13% 11% 3	1484
December	1st to 10th	Day	66% 5% 12% 11% 5%	2280
	11th to 20th	Day	64% 4 9% 15% 8%	2618
	21st to end	Day	64% 7% 9% 11% 8% 1	3713
January	1st to 10th	Night	70% 6% 10% 10% 5%	6349
	11th to 20th	Night	71% 7% 9% 11% 3	6360
	21st to end	Night	57% 7% 10% 15% 11%	6996
February	1st to 10th	Night	63% 5% 9% 15% 8% 1	2795
	11th to 20th	Night	64% 6% 9% 13% 8% 1	2340
	21st to end	Night	58% 4 10% 15% 11% 1	1980
March	1st to 10th	Night	62% 5% 9% 12% 10% 1	5374
	11th to 20th	Night	59% 7% 13% 13% 8% 1	5218
	21st to end	Night	59% 4 6% 20% 9% 1	5102
April	1st to 10th	Night	57% 5% 10% 15% 11% 2	2000
	11th to 20th	Night	53% 5% 8% 20% 11% 2	1889
	21st to end	Night	55% 4 8% 17% 13% 2	1800
May	1st to 10th	Night	57% 6% 12% 14% 10% 1	3969
	11th to 20th	Night	53% 7% 11% 19% 9% 1	3576
	21st to end	Night	48% 6% 14% 16% 15% 2	3927
June	1st to 10th	Night	51% 7% 11% 20% 10% 1	1423
	11th to 20th	Night	47% 8% 11% 20% 12% 2	1400
	21st to end	Night	53% 7% 12% 17% 10% 1	1416
July	1st to 10th	Night	47% 9% 19% 19% 6%	2560
	11th to 20th	Night	46% 8% 20% 20% 6%	2552
	21st to end	Night	41% 9% 19% 24% 8%	2651
August	1st to 10th	Night	48% 9% 16% 22% 5%	2496
	11th to 20th	Night	50% 11% 16% 17% 5%	2802
	21st to end	Night	47% 8% 13% 20% 12%	3341
September	1st to 10th	Night	43% 8% 14% 24% 11% 1	1900
	11th to 20th	Night	39% 7% 16% 28% 9% 1	2064
	21st to end	Night	43% 7% 12% 24% 12%	2090
October	1st to 10th	Night	49% 7% 13% 24% 7%	3498
	11th to 20th	Night	52% 6% 15% 25% 3	4033
	21st to end	Night	51% 6% 18% 16% 9%	4467
November	1st to 10th	Night	56% 6% 13% 18% 6%	2537
	11th to 20th	Night	57% 6% 13% 16% 8%	2600
	21st to end	Night	65% 5% 11% 13% 5%	2910
December	1st to 10th	Night	70% 6% 11% 11% 2	4910
	11th to 20th	Night	65% 6% 8% 17% 5%	5592
	21st to end	Night	64% 5% 8% 16% 7%	7249

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	35% 21% 28% 15% 1 1	200
	11th to 20th	Day	25% 27% 33% 10% 6%	200
	21st to end	Day	22% 24% 35% 15% 4	220
February	1st to 10th	Day	25% 27% 36% 9% 2 1	203
	11th to 20th	Day	27% 23% 35% 13% 2	495
	21st to end	Day	25% 25% 31% 16% 3	414
March	1st to 10th	Day	29% 21% 29% 17% 4	500
	11th to 20th	Day	27% 21% 30% 16% 5% 1	500
	21st to end	Day	27% 21% 29% 15% 7% 2	550
April	1st to 10th	Day	34% 17% 28% 16% 5%	500
	11th to 20th	Day	31% 18% 27% 17% 5% 1	492
	21st to end	Day	32% 18% 30% 13% 5% 1	500
May	1st to 10th	Day	30% 17% 31% 17% 4 1	503
	11th to 20th	Day	23% 12% 32% 22% 10% 1	527
	21st to end	Day	23% 20% 32% 16% 8%	573
June	1st to 10th	Day	23% 13% 32% 24% 7% 1	703
	11th to 20th	Day	22% 12% 30% 25% 11% 1	730
	21st to end	Day	27% 12% 27% 22% 11% 1	708
July	1st to 10th	Day	18% 13% 32% 26% 11% 2	525
	11th to 20th	Day	17% 13% 35% 24% 9% 2	524
	21st to end	Day	18% 8% 33% 29% 10% 2	532
August	1st to 10th	Day	19% 12% 26% 28% 11% 3	486
	11th to 20th	Day	21% 7% 24% 27% 17% 3	479
	21st to end	Day	22% 15% 24% 19% 14% 6%	539
September	1st to 10th	Day	19% 12% 27% 27% 11% 4	490
	11th to 20th	Day	19% 10% 26% 25% 16% 4	490
	21st to end	Day	21% 14% 25% 23% 14% 3	490
October	1st to 10th	Day	24% 14% 27% 23% 10% 2	490
	11th to 20th	Day	29% 18% 25% 18% 9% 1	410
	21st to end	Day	35% 15% 26% 20% 4	429
November	1st to 10th	Day	33% 15% 30% 16% 5% 1	395
	11th to 20th	Day	29% 20% 28% 16% 7% 1	400
	21st to end	Day	38% 18% 29% 13% 2	209
December	1st to 10th	Day	32% 16% 29% 17% 6% 1	200
	11th to 20th	Day	34% 21% 30% 11% 4 1	200
	21st to end	Day	33% 22% 27% 14% 3 1	220
January	1st to 10th	Night	28% 19% 34% 17% 3	800
	11th to 20th	Night	26% 18% 33% 20% 4	800
	21st to end	Night	17% 14% 37% 28% 5%	880
February	1st to 10th	Night	21% 15% 36% 23% 4	800
	11th to 20th	Night	23% 20% 38% 17% 3	783
	21st to end	Night	26% 15% 33% 23% 3	660
March	1st to 10th	Night	26% 14% 35% 21% 3	800
	11th to 20th	Night	27% 15% 34% 19% 5% 1	800
	21st to end	Night	25% 13% 32% 24% 6%	880
April	1st to 10th	Night	31% 15% 30% 20% 5%	800
	11th to 20th	Night	27% 12% 33% 23% 5%	705
	21st to end	Night	31% 14% 29% 21% 5%	600
May	1st to 10th	Night	27% 10% 32% 25% 6%	561
	11th to 20th	Night	23% 12% 29% 31% 4 1	394
	21st to end	Night	23% 10% 31% 30% 6%	433
June	1st to 10th	Night	26% 8% 30% 32% 6%	400
	11th to 20th	Night	21% 8% 27% 37% 8%	400
	21st to end	Night	24% 7% 29% 33% 8%	400
July	1st to 10th	Night	17% 6% 34% 35% 8%	390
	11th to 20th	Night	18% 5% 25% 39% 12% 1	388
	21st to end	Night	14% 7% 23% 47% 8%	416
August	1st to 10th	Night	18% 3 22% 40% 16% 1	378
	11th to 20th	Night	18% 5% 24% 37% 14% 2	555
	21st to end	Night	18% 7% 27% 32% 15% 1	753
September	1st to 10th	Night	20% 6% 28% 33% 12% 1	760
	11th to 20th	Night	20% 7% 24% 31% 16% 2	760
	21st to end	Night	21% 8% 28% 28% 14% 1	760
October	1st to 10th	Night	23% 9% 26% 32% 8% 1	760
	11th to 20th	Night	29% 11% 28% 22% 8% 1	760
	21st to end	Night	32% 12% 32% 19% 5%	836
November	1st to 10th	Night	28% 16% 28% 23% 6%	780
	11th to 20th	Night	25% 16% 29% 20% 9% 1	800
	21st to end	Night	31% 17% 28% 18% 5% 1	860
December	1st to 10th	Night	31% 15% 30% 18% 6%	900
	11th to 20th	Night	28% 19% 27% 19% 6% 1	900
	21st to end	Night	33% 16% 30% 16% 3 1	935

Page generated at 2025-07-18 01:09:59. Version ac07

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