Observatoire de Saint-Camille
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Observatoire de Saint-Camille clear sky chart from 2005-11-06 to 2025-02-06.

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% 12% 4 10% 6% 5% 5% 4 5% 6% 26%	107878
	Night	18% 15% 5% 11% 6% 5% 4 3 4 5% 25%	110384
Transparency	Day	60% 3 11% 18% 7% 1	111394
	Night	63% 3 10% 17% 8% 1	115033
Seeing	Day	28% 16% 28% 18% 8% 2	14882
	Night	27% 13% 25% 25% 9% 1	24036

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	16% 21% 9% 20% 7% 8% 5% 2 2 2 9%	3597
	11th to 20th	Day	10% 15% 8% 26% 15% 4 4 2 2 2 12%	3570
	21st to end	Day	9% 18% 9% 14% 7% 10% 7% 3 4 4 16%	3960
February	1st to 10th	Day	14% 19% 6% 15% 9% 6% 4 3 4 3 17%	1605
	11th to 20th	Day	14% 23% 7% 14% 7% 5% 4 3 3 4 16%	1848
	21st to end	Day	14% 18% 6% 12% 8% 6% 4 3 4 4 20%	1570
March	1st to 10th	Day	21% 16% 4 11% 6% 5% 4 3 4 4 23%	3116
	11th to 20th	Day	17% 21% 6% 13% 5% 4 4 3 3 4 21%	3303
	21st to end	Day	18% 16% 5% 11% 4 4 3 2 3 4 31%	4092
April	1st to 10th	Day	23% 16% 3 10% 5% 4 4 3 4 4 24%	2280
	11th to 20th	Day	20% 13% 3 7% 5% 4 4 2 4 5% 33%	2309
	21st to end	Day	24% 13% 4 7% 4 3 3 3 4 5% 28%	2470
May	1st to 10th	Day	24% 9% 3 8% 5% 5% 4 3 5% 6% 27%	4165
	11th to 20th	Day	20% 8% 3 7% 6% 5% 5% 4 6% 7% 28%	4398
	21st to end	Day	17% 7% 3 8% 5% 5% 6% 5% 7% 7% 30%	4837
June	1st to 10th	Day	27% 8% 3 7% 4 4 5% 4 6% 7% 26%	2660
	11th to 20th	Day	19% 6% 3 7% 4 5% 5% 5% 5% 9% 32%	2660
	21st to end	Day	24% 8% 3 9% 5% 5% 5% 3 5% 7% 26%	2660
July	1st to 10th	Day	15% 8% 3 8% 6% 6% 6% 5% 7% 8% 29%	4440
	11th to 20th	Day	17% 7% 3 8% 6% 6% 5% 5% 6% 8% 30%	4440
	21st to end	Day	17% 7% 2 5% 4 4 4 4 6% 7% 39%	4814
August	1st to 10th	Day	20% 6% 2 8% 6% 5% 6% 5% 7% 8% 27%	4375
	11th to 20th	Day	19% 8% 3 8% 5% 5% 6% 5% 8% 8% 25%	4045
	21st to end	Day	22% 7% 2 6% 4 4 4 4 5% 7% 35%	4247
September	1st to 10th	Day	18% 7% 2 6% 5% 4 4 3 6% 7% 38%	2280
	11th to 20th	Day	20% 6% 2 5% 3 3 4 3 6% 6% 41%	2121
	21st to end	Day	21% 8% 3 5% 3 4 4 3 7% 9% 33%	2090
October	1st to 10th	Day	24% 10% 3 6% 4 5% 4 3 5% 6% 29%	2079
	11th to 20th	Day	21% 15% 4 7% 4 5% 5% 4 5% 5% 25%	1769
	21st to end	Day	27% 17% 4 8% 4 3 4 3 3 4 22%	1881
November	1st to 10th	Day	20% 18% 4 8% 4 4 3 3 4 5% 27%	1761
	11th to 20th	Day	19% 19% 7% 9% 5% 3 3 3 4 4 23%	1800
	21st to end	Day	20% 22% 6% 10% 5% 5% 4 3 4 4 18%	1633
December	1st to 10th	Day	17% 22% 8% 16% 9% 4 4 3 3 3 11%	2317
	11th to 20th	Day	19% 17% 9% 13% 6% 3 4 3 4 4 21%	2726
	21st to end	Day	19% 20% 6% 13% 5% 4 4 2 3 5% 18%	3960
January	1st to 10th	Night	13% 21% 10% 20% 9% 5% 3 2 3 3 11%	6349
	11th to 20th	Night	9% 21% 9% 23% 10% 5% 4 3 3 3 10%	6315
	21st to end	Night	9% 17% 7% 14% 9% 7% 6% 4 4 4 19%	6996
February	1st to 10th	Night	13% 19% 6% 14% 8% 6% 4 3 3 5% 20%	2680
	11th to 20th	Night	13% 19% 6% 14% 8% 6% 4 3 4 4 19%	2218
	21st to end	Night	15% 16% 6% 11% 6% 6% 4 3 4 4 25%	1884
March	1st to 10th	Night	23% 17% 4 8% 4 3 4 2 3 4 28%	3724
	11th to 20th	Night	17% 21% 7% 11% 6% 4 4 2 3 3 22%	3655
	21st to end	Night	17% 16% 5% 10% 7% 4 3 3 3 4 28%	3539
April	1st to 10th	Night	23% 15% 4 8% 4 4 3 3 5% 4 28%	1900
	11th to 20th	Night	21% 12% 3 7% 4 4 4 3 4 5% 33%	1820
	21st to end	Night	22% 13% 3 8% 4 4 4 3 4 6% 29%	1710
May	1st to 10th	Night	27% 9% 3 8% 4 4 4 3 5% 6% 28%	2803
	11th to 20th	Night	21% 9% 3 6% 4 4 4 4 5% 7% 32%	2495
	21st to end	Night	18% 7% 3 6% 4 4 5% 4 5% 7% 37%	2738
June	1st to 10th	Night	26% 9% 2 7% 3 3 4 4 7% 7% 27%	1520
	11th to 20th	Night	21% 7% 2 5% 3 3 5% 4 6% 9% 35%	1520
	21st to end	Night	21% 9% 2 8% 6% 5% 4 4 5% 7% 29%	1520
July	1st to 10th	Night	14% 8% 4 9% 6% 5% 6% 4 6% 8% 30%	2520
	11th to 20th	Night	17% 8% 3 6% 5% 5% 5% 4 5% 7% 34%	2520
	21st to end	Night	16% 7% 2 6% 4 4 4 4 6% 7% 39%	2739
August	1st to 10th	Night	24% 8% 2 7% 4 5% 4 3 6% 7% 30%	2524
	11th to 20th	Night	17% 9% 3 8% 6% 5% 5% 4 6% 7% 29%	2782
	21st to end	Night	19% 8% 3 7% 4 4 4 4 4 7% 37%	3406
September	1st to 10th	Night	19% 8% 3 7% 4 4 4 3 5% 5% 39%	1900
	11th to 20th	Night	17% 5% 2 5% 3 3 4 3 5% 6% 46%	2058
	21st to end	Night	20% 7% 2 6% 4 4 4 3 4 6% 41%	2090
October	1st to 10th	Night	20% 8% 3 7% 4 4 4 3 4 6% 35%	2099
	11th to 20th	Night	23% 13% 3 7% 5% 4 4 3 4 5% 28%	2410
	21st to end	Night	26% 14% 3 7% 5% 3 4 4 5% 4 26%	2717
November	1st to 10th	Night	21% 16% 4 9% 4 4 3 3 5% 5% 26%	2537
	11th to 20th	Night	18% 16% 6% 10% 5% 4 4 3 4 5% 27%	2600
	21st to end	Night	19% 20% 6% 12% 5% 4 3 2 4 4 21%	2765
December	1st to 10th	Night	16% 21% 11% 20% 7% 3 4 2 2 3 10%	4864
	11th to 20th	Night	20% 20% 6% 15% 6% 4 4 3 3 3 17%	5471
	21st to end	Night	20% 20% 5% 11% 5% 4 4 2 3 6% 21%	6996

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	86% 2 5% 7% 1	3598
	11th to 20th	Day	82% 2 4 9% 2 1	3600
	21st to end	Day	74% 2 5% 10% 8% 1	3960
February	1st to 10th	Day	74% 3 5% 11% 6% 1	1605
	11th to 20th	Day	75% 2 7% 10% 5% 1	1857
	21st to end	Day	68% 4 7% 14% 6% 2	1570
March	1st to 10th	Day	67% 2 7% 13% 9% 2	3119
	11th to 20th	Day	70% 2 8% 12% 8% 1	3303
	21st to end	Day	60% 3 5% 16% 15% 2	4092
April	1st to 10th	Day	64% 3 8% 15% 8% 2	2280
	11th to 20th	Day	55% 2 7% 21% 12% 1	2309
	21st to end	Day	60% 2 8% 17% 11% 2	2470
May	1st to 10th	Day	58% 3 9% 20% 8% 1	4179
	11th to 20th	Day	55% 3 18% 16% 7% 1	4402
	21st to end	Day	51% 4 12% 22% 11%	4837
June	1st to 10th	Day	57% 5% 10% 21% 7% 1	2660
	11th to 20th	Day	49% 5% 13% 22% 10% 1	2660
	21st to end	Day	58% 5% 11% 19% 7%	2660
July	1st to 10th	Day	51% 3 15% 25% 7%	4370
	11th to 20th	Day	50% 3 16% 27% 4	4365
	21st to end	Day	45% 4 13% 31% 6%	4661
August	1st to 10th	Day	54% 4 17% 21% 4	4361
	11th to 20th	Day	54% 4 19% 18% 4	4084
	21st to end	Day	49% 3 14% 20% 12% 1	4247
September	1st to 10th	Day	46% 5% 14% 25% 9% 1	2280
	11th to 20th	Day	43% 5% 11% 29% 12%	2121
	21st to end	Day	48% 4 12% 25% 10% 1	2090
October	1st to 10th	Day	53% 3 13% 24% 6%	3456
	11th to 20th	Day	56% 2 13% 25% 4	2920
	21st to end	Day	57% 3 14% 19% 7%	3081
November	1st to 10th	Day	61% 3 11% 18% 7%	1761
	11th to 20th	Day	65% 3 9% 14% 8% 1	1800
	21st to end	Day	70% 4 11% 12% 3	1633
December	1st to 10th	Day	80% 2 8% 7% 3	2317
	11th to 20th	Day	69% 3 6% 15% 7%	2726
	21st to end	Day	72% 2 6% 11% 9% 1	3960
January	1st to 10th	Night	82% 2 7% 7% 3	6349
	11th to 20th	Night	83% 2 6% 7% 2	6360
	21st to end	Night	70% 2 7% 11% 10%	6996
February	1st to 10th	Night	70% 3 7% 13% 6% 1	2680
	11th to 20th	Night	71% 3 7% 12% 7%	2220
	21st to end	Night	64% 3 7% 14% 10% 1	1884
March	1st to 10th	Night	63% 2 9% 16% 8% 2	3734
	11th to 20th	Night	70% 3 6% 13% 8% 1	3656
	21st to end	Night	63% 2 6% 18% 10% 2	3539
April	1st to 10th	Night	60% 3 8% 18% 11% 1	1900
	11th to 20th	Night	54% 3 7% 23% 11% 2	1820
	21st to end	Night	58% 4 8% 18% 10% 2	1710
May	1st to 10th	Night	58% 3 12% 19% 8% 1	2809
	11th to 20th	Night	52% 4 13% 21% 8% 1	2496
	21st to end	Night	47% 4 13% 19% 16% 1	2739
June	1st to 10th	Night	54% 4 11% 21% 9%	1520
	11th to 20th	Night	46% 4 12% 24% 12% 2	1520
	21st to end	Night	55% 4 12% 19% 9%	1520
July	1st to 10th	Night	52% 3 17% 19% 9%	2480
	11th to 20th	Night	49% 4 16% 24% 6%	2472
	21st to end	Night	46% 4 16% 26% 7%	2651
August	1st to 10th	Night	55% 4 14% 23% 4	2514
	11th to 20th	Night	55% 5% 15% 18% 6%	2809
	21st to end	Night	48% 3 12% 23% 13% 1	3406
September	1st to 10th	Night	48% 5% 11% 25% 11% 1	1900
	11th to 20th	Night	39% 4 14% 31% 10% 1	2058
	21st to end	Night	45% 4 11% 27% 11% 1	2090
October	1st to 10th	Night	53% 2 9% 26% 9%	3502
	11th to 20th	Night	56% 3 11% 25% 5%	3998
	21st to end	Night	55% 3 13% 19% 9% 2	4467
November	1st to 10th	Night	61% 3 11% 18% 6% 1	2537
	11th to 20th	Night	62% 3 10% 15% 9% 1	2600
	21st to end	Night	69% 3 10% 13% 4	2765
December	1st to 10th	Night	83% 2 7% 7% 2	4864
	11th to 20th	Night	75% 2 5% 12% 6%	5472
	21st to end	Night	68% 2 8% 14% 8%	6996

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	29% 23% 33% 13% 2 1	200
	11th to 20th	Day	32% 23% 31% 13% 3	200
	21st to end	Day	30% 23% 30% 13% 4 1	220
February	1st to 10th	Day	39% 28% 23% 7% 2 1	215
	11th to 20th	Day	33% 25% 30% 9% 2 1	456
	21st to end	Day	32% 22% 27% 18% 2	382
March	1st to 10th	Day	31% 22% 26% 17% 4	460
	11th to 20th	Day	32% 23% 24% 16% 3 2	460
	21st to end	Day	33% 19% 26% 13% 8% 1	506
April	1st to 10th	Day	37% 17% 25% 13% 7% 1	460
	11th to 20th	Day	33% 21% 24% 14% 6% 2	452
	21st to end	Day	35% 17% 28% 12% 5% 2	460
May	1st to 10th	Day	32% 19% 26% 15% 7% 1	463
	11th to 20th	Day	27% 16% 28% 21% 7% 2	487
	21st to end	Day	24% 21% 29% 19% 5% 1	529
June	1st to 10th	Day	30% 16% 29% 18% 6% 1	490
	11th to 20th	Day	22% 17% 29% 23% 8% 1	490
	21st to end	Day	26% 16% 32% 17% 7% 2	490
July	1st to 10th	Day	19% 12% 33% 26% 9% 1	485
	11th to 20th	Day	19% 9% 39% 23% 8% 2	484
	21st to end	Day	22% 9% 33% 29% 6% 1	532
August	1st to 10th	Day	21% 12% 28% 24% 14% 1	486
	11th to 20th	Day	22% 8% 25% 27% 16% 3	479
	21st to end	Day	24% 12% 23% 21% 13% 6%	539
September	1st to 10th	Day	19% 10% 33% 21% 12% 5%	490
	11th to 20th	Day	21% 8% 22% 24% 17% 8%	490
	21st to end	Day	21% 12% 25% 24% 12% 5%	490
October	1st to 10th	Day	25% 16% 24% 17% 14% 4	490
	11th to 20th	Day	33% 14% 25% 15% 11% 2	420
	21st to end	Day	40% 16% 21% 17% 6%	429
November	1st to 10th	Day	36% 15% 27% 18% 4	395
	11th to 20th	Day	33% 17% 26% 17% 6% 1	400
	21st to end	Day	35% 20% 27% 15% 3	233
December	1st to 10th	Day	38% 16% 27% 15% 5% 1	200
	11th to 20th	Day	38% 21% 29% 10% 3 1	200
	21st to end	Day	39% 20% 29% 8% 4 1	220
January	1st to 10th	Night	28% 20% 30% 18% 3	800
	11th to 20th	Night	28% 20% 29% 19% 5%	800
	21st to end	Night	22% 17% 31% 23% 5% 1	880
February	1st to 10th	Night	24% 19% 32% 20% 5%	781
	11th to 20th	Night	24% 20% 33% 19% 3	743
	21st to end	Night	26% 18% 29% 23% 4	628
March	1st to 10th	Night	29% 16% 30% 22% 3	760
	11th to 20th	Night	29% 16% 28% 22% 5% 1	760
	21st to end	Night	26% 16% 25% 24% 8% 1	836
April	1st to 10th	Night	32% 14% 25% 23% 5%	760
	11th to 20th	Night	30% 14% 26% 23% 7%	696
	21st to end	Night	29% 18% 26% 19% 7%	570
May	1st to 10th	Night	30% 11% 29% 22% 8%	552
	11th to 20th	Night	24% 10% 27% 31% 7% 1	374
	21st to end	Night	24% 8% 27% 32% 8%	411
June	1st to 10th	Night	31% 7% 22% 32% 8% 1	380
	11th to 20th	Night	22% 7% 23% 33% 14%	380
	21st to end	Night	23% 6% 23% 37% 10% 1	380
July	1st to 10th	Night	16% 5% 27% 37% 13% 1	370
	11th to 20th	Night	16% 5% 21% 43% 13% 2	368
	21st to end	Night	18% 5% 19% 42% 17%	416
August	1st to 10th	Night	20% 4 15% 41% 20% 1	383
	11th to 20th	Night	19% 5% 19% 36% 20% 1	562
	21st to end	Night	21% 4 21% 32% 20% 2	792
September	1st to 10th	Night	21% 7% 21% 34% 14% 2	760
	11th to 20th	Night	20% 5% 20% 30% 23% 2	760
	21st to end	Night	24% 8% 22% 28% 16% 2	760
October	1st to 10th	Night	25% 11% 22% 27% 14% 1	760
	11th to 20th	Night	31% 11% 22% 25% 9% 2	760
	21st to end	Night	32% 14% 26% 23% 4	836
November	1st to 10th	Night	31% 15% 24% 21% 8%	780
	11th to 20th	Night	28% 17% 27% 19% 9% 1	800
	21st to end	Night	32% 19% 22% 21% 5% 1	800
December	1st to 10th	Night	35% 17% 26% 16% 6%	885
	11th to 20th	Night	33% 20% 22% 19% 6%	873
	21st to end	Night	35% 18% 23% 19% 5%	880

Page generated at 2025-02-03 03:05:55. Version ac07

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