Observatoire de St-Felicien
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Observatoire de St-Felicien clear sky chart from 2005-11-06 to 2024-11-04.

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	15% 10% 4 9% 6% 6% 5% 4 6% 7% 28%	101589
	Night	14% 12% 4 10% 6% 5% 5% 4 5% 6% 27%	97418
Transparency	Day	54% 6% 13% 18% 8% 1	105012
	Night	57% 6% 13% 17% 6%	102086
Seeing	Day	20% 11% 31% 25% 11% 3	15151
	Night	22% 10% 31% 27% 9% 1	23554

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	11% 16% 7% 15% 7% 7% 6% 4 4 5% 16%	2500
	11th to 20th	Day	10% 13% 6% 16% 9% 8% 7% 5% 6% 5% 15%	2520
	21st to end	Day	7% 13% 4 15% 8% 6% 5% 4 5% 6% 26%	2772
February	1st to 10th	Day	6% 13% 5% 12% 9% 9% 8% 5% 6% 5% 21%	1520
	11th to 20th	Day	11% 13% 6% 12% 10% 7% 6% 3 4 6% 20%	1747
	21st to end	Day	10% 14% 4 12% 7% 6% 5% 4 8% 5% 25%	1570
March	1st to 10th	Day	12% 14% 4 8% 6% 5% 5% 4 5% 5% 32%	3116
	11th to 20th	Day	13% 17% 5% 11% 7% 6% 5% 3 5% 6% 23%	3245
	21st to end	Day	11% 13% 3 10% 5% 4 5% 5% 6% 7% 30%	4163
April	1st to 10th	Day	16% 16% 4 12% 8% 4 4 3 4 5% 24%	2280
	11th to 20th	Day	17% 10% 4 8% 5% 5% 4 4 5% 7% 33%	2328
	21st to end	Day	20% 10% 4 9% 5% 4 4 4 5% 5% 30%	2470
May	1st to 10th	Day	15% 10% 3 8% 5% 6% 6% 4 6% 7% 31%	4426
	11th to 20th	Day	16% 8% 3 8% 5% 5% 5% 4 6% 8% 32%	4398
	21st to end	Day	14% 8% 3 8% 5% 5% 6% 5% 6% 7% 34%	4987
June	1st to 10th	Day	18% 8% 3 8% 5% 5% 6% 4 6% 7% 29%	2850
	11th to 20th	Day	15% 7% 3 7% 5% 5% 5% 4 7% 8% 33%	2850
	21st to end	Day	21% 8% 3 7% 6% 5% 6% 5% 6% 6% 27%	2850
July	1st to 10th	Day	15% 8% 3 7% 5% 5% 6% 5% 7% 9% 29%	4632
	11th to 20th	Day	12% 7% 3 8% 6% 6% 6% 5% 8% 9% 29%	4440
	21st to end	Day	12% 7% 3 8% 6% 5% 6% 4 7% 8% 35%	4814
August	1st to 10th	Day	14% 7% 3 8% 7% 7% 7% 6% 8% 9% 24%	4423
	11th to 20th	Day	14% 8% 3 7% 5% 6% 7% 5% 8% 9% 28%	4182
	21st to end	Day	12% 7% 3 9% 6% 6% 5% 4 6% 8% 33%	4291
September	1st to 10th	Day	15% 7% 3 8% 6% 5% 6% 4 6% 8% 32%	2280
	11th to 20th	Day	15% 7% 3 8% 5% 5% 4 4 6% 8% 35%	2164
	21st to end	Day	21% 9% 3 8% 5% 5% 5% 3 4 7% 31%	2090
October	1st to 10th	Day	17% 10% 3 9% 6% 5% 5% 4 6% 6% 30%	2004
	11th to 20th	Day	23% 14% 5% 11% 6% 5% 5% 3 4 6% 18%	1762
	21st to end	Day	24% 13% 3 9% 5% 5% 4 4 5% 5% 23%	1881
November	1st to 10th	Day	17% 13% 4 12% 7% 6% 4 3 4 4 24%	1698
	11th to 20th	Day	17% 15% 5% 12% 7% 4 4 4 6% 5% 21%	1577
	21st to end	Day	19% 17% 4 11% 6% 6% 5% 4 5% 6% 16%	1330
December	1st to 10th	Day	16% 19% 4 11% 9% 4 5% 4 6% 5% 18%	1330
	11th to 20th	Day	20% 17% 5% 9% 5% 4 3 2 4 5% 26%	1668
	21st to end	Day	16% 15% 6% 11% 9% 7% 6% 5% 5% 4 16%	2431
January	1st to 10th	Night	13% 19% 6% 14% 10% 6% 5% 3 4 4 15%	4429
	11th to 20th	Night	10% 14% 6% 16% 11% 7% 5% 3 4 5% 19%	4440
	21st to end	Night	7% 13% 6% 16% 9% 7% 5% 5% 5% 6% 21%	4884
February	1st to 10th	Night	9% 13% 5% 11% 7% 8% 6% 5% 5% 7% 24%	2660
	11th to 20th	Night	8% 16% 6% 14% 10% 6% 6% 4 4 5% 21%	2314
	21st to end	Night	10% 14% 6% 10% 6% 5% 6% 4 5% 6% 27%	1884
March	1st to 10th	Night	15% 12% 4 9% 6% 6% 7% 5% 5% 6% 24%	3724
	11th to 20th	Night	13% 17% 6% 12% 7% 6% 5% 3 5% 5% 21%	3713
	21st to end	Night	11% 14% 4 11% 6% 6% 6% 4 6% 7% 27%	3466
April	1st to 10th	Night	19% 15% 4 9% 6% 5% 5% 3 5% 5% 25%	1900
	11th to 20th	Night	18% 10% 2 8% 5% 5% 5% 4 5% 6% 32%	1801
	21st to end	Night	17% 11% 3 8% 6% 5% 3 3 6% 5% 32%	1710
May	1st to 10th	Night	14% 11% 3 8% 6% 6% 5% 4 5% 6% 33%	2530
	11th to 20th	Night	14% 10% 3 8% 6% 5% 6% 4 5% 6% 32%	2495
	21st to end	Night	18% 8% 3 7% 5% 5% 5% 4 5% 8% 31%	2591
June	1st to 10th	Night	18% 8% 2 7% 5% 4 6% 5% 6% 8% 30%	1330
	11th to 20th	Night	14% 9% 3 7% 4 6% 4 5% 6% 7% 36%	1330
	21st to end	Night	17% 7% 3 9% 5% 5% 6% 4 7% 7% 31%	1330
July	1st to 10th	Night	11% 6% 3 9% 6% 5% 8% 5% 8% 8% 30%	2329
	11th to 20th	Night	10% 7% 2 8% 6% 5% 6% 5% 8% 8% 36%	2520
	21st to end	Night	10% 5% 2 7% 4 5% 6% 4 7% 8% 42%	2739
August	1st to 10th	Night	13% 6% 3 7% 5% 6% 5% 5% 8% 9% 34%	2506
	11th to 20th	Night	16% 8% 2 7% 5% 4 3 4 7% 9% 35%	2615
	21st to end	Night	13% 7% 2 6% 5% 5% 5% 5% 6% 7% 38%	3348
September	1st to 10th	Night	15% 8% 3 6% 4 4 4 3 5% 7% 40%	1900
	11th to 20th	Night	18% 7% 3 7% 4 4 3 4 5% 5% 40%	2015
	21st to end	Night	18% 7% 3 7% 5% 5% 4 5% 5% 6% 35%	2090
October	1st to 10th	Night	17% 10% 2 6% 5% 5% 5% 3 6% 8% 34%	2175
	11th to 20th	Night	25% 12% 3 7% 5% 5% 5% 3 5% 5% 24%	2418
	21st to end	Night	24% 13% 3 8% 5% 5% 5% 4 5% 6% 22%	2717
November	1st to 10th	Night	19% 13% 4 9% 5% 5% 5% 4 5% 7% 24%	2453
	11th to 20th	Night	18% 13% 5% 11% 6% 5% 5% 4 5% 6% 22%	2598
	21st to end	Night	18% 17% 5% 12% 7% 6% 5% 4 5% 5% 16%	2847
December	1st to 10th	Night	16% 18% 6% 13% 7% 5% 4 3 4 4 19%	2850
	11th to 20th	Night	19% 16% 5% 9% 6% 5% 5% 4 5% 5% 21%	3531
	21st to end	Night	14% 18% 7% 14% 7% 6% 4 3 4 4 20%	5236

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	69% 7% 13% 9% 3	2501
	11th to 20th	Day	68% 7% 12% 10% 4	2520
	21st to end	Day	57% 6% 11% 17% 9%	2772
February	1st to 10th	Day	63% 5% 9% 14% 8% 1	1520
	11th to 20th	Day	65% 6% 9% 13% 7%	1756
	21st to end	Day	57% 7% 9% 16% 8% 2	1570
March	1st to 10th	Day	50% 8% 12% 17% 10% 2	3119
	11th to 20th	Day	61% 6% 11% 17% 6%	3245
	21st to end	Day	48% 7% 11% 17% 15% 2	4163
April	1st to 10th	Day	63% 4 9% 13% 9% 2	2280
	11th to 20th	Day	51% 5% 9% 21% 11% 2	2328
	21st to end	Day	55% 5% 8% 18% 13% 1	2470
May	1st to 10th	Day	48% 8% 14% 17% 12% 1	4440
	11th to 20th	Day	46% 9% 12% 22% 10% 1	4402
	21st to end	Day	45% 8% 10% 19% 16% 2	4987
June	1st to 10th	Day	53% 7% 9% 20% 11% 1	2850
	11th to 20th	Day	46% 7% 12% 21% 12% 2	2850
	21st to end	Day	54% 8% 11% 18% 9%	2850
July	1st to 10th	Day	49% 5% 14% 28% 3	4561
	11th to 20th	Day	49% 6% 18% 22% 5%	4365
	21st to end	Day	47% 6% 17% 23% 8%	4661
August	1st to 10th	Day	54% 6% 16% 21% 3	4409
	11th to 20th	Day	50% 6% 21% 19% 4	4224
	21st to end	Day	49% 5% 14% 22% 10%	4291
September	1st to 10th	Day	48% 8% 16% 21% 8%	2280
	11th to 20th	Day	47% 7% 18% 22% 6%	2164
	21st to end	Day	53% 7% 14% 19% 6%	2090
October	1st to 10th	Day	56% 4 13% 22% 4 1	3329
	11th to 20th	Day	66% 4 15% 14% 2	2900
	21st to end	Day	60% 5% 17% 14% 3	3081
November	1st to 10th	Day	63% 5% 13% 13% 5% 1	1698
	11th to 20th	Day	65% 5% 15% 12% 4	1577
	21st to end	Day	68% 5% 15% 9% 2	1330
December	1st to 10th	Day	68% 6% 12% 10% 3	1330
	11th to 20th	Day	62% 4 11% 19% 5%	1668
	21st to end	Day	69% 7% 10% 8% 6%	2431
January	1st to 10th	Night	73% 4 11% 8% 3	4429
	11th to 20th	Night	68% 5% 11% 12% 4	4440
	21st to end	Night	62% 7% 11% 15% 5%	4884
February	1st to 10th	Night	59% 5% 11% 17% 8%	2660
	11th to 20th	Night	66% 5% 10% 13% 6%	2316
	21st to end	Night	57% 6% 11% 18% 8%	1884
March	1st to 10th	Night	60% 6% 11% 15% 7% 1	3734
	11th to 20th	Night	64% 7% 10% 13% 6% 1	3714
	21st to end	Night	54% 5% 12% 19% 8% 2	3466
April	1st to 10th	Night	61% 4 10% 15% 7% 2	1900
	11th to 20th	Night	51% 4 11% 22% 11%	1801
	21st to end	Night	53% 5% 9% 20% 12% 1	1710
May	1st to 10th	Night	48% 9% 12% 17% 13% 1	2536
	11th to 20th	Night	45% 11% 14% 18% 10% 1	2496
	21st to end	Night	50% 6% 11% 18% 14% 1	2592
June	1st to 10th	Night	49% 9% 12% 21% 9% 1	1330
	11th to 20th	Night	45% 8% 11% 21% 12% 3	1330
	21st to end	Night	48% 9% 12% 19% 11%	1330
July	1st to 10th	Night	48% 6% 14% 27% 5%	2291
	11th to 20th	Night	44% 5% 19% 26% 5%	2472
	21st to end	Night	39% 7% 20% 23% 11%	2651
August	1st to 10th	Night	46% 7% 18% 23% 6%	2496
	11th to 20th	Night	46% 6% 22% 21% 4	2639
	21st to end	Night	43% 6% 17% 26% 8%	3348
September	1st to 10th	Night	43% 7% 17% 24% 9%	1900
	11th to 20th	Night	46% 7% 18% 23% 6%	2015
	21st to end	Night	49% 8% 13% 24% 7%	2090
October	1st to 10th	Night	50% 4 17% 24% 5%	3630
	11th to 20th	Night	61% 4 14% 17% 4	4019
	21st to end	Night	61% 5% 14% 14% 7%	4467
November	1st to 10th	Night	59% 7% 14% 14% 5%	2453
	11th to 20th	Night	64% 6% 14% 13% 4	2598
	21st to end	Night	68% 8% 13% 9% 2	2847
December	1st to 10th	Night	69% 6% 13% 10% 2	2850
	11th to 20th	Night	63% 7% 13% 13% 5%	3532
	21st to end	Night	68% 5% 12% 10% 4 1	5236

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	22% 12% 28% 29% 8% 1	180
	11th to 20th	Day	16% 11% 29% 31% 13%	180
	21st to end	Day	15% 5% 29% 35% 14% 3	198
February	1st to 10th	Day	11% 12% 42% 24% 9% 1	180
	11th to 20th	Day	17% 13% 37% 28% 4	356
	21st to end	Day	19% 12% 41% 21% 6% 1	382
March	1st to 10th	Day	21% 16% 30% 22% 9% 1	460
	11th to 20th	Day	20% 13% 34% 22% 9% 1	460
	21st to end	Day	21% 14% 32% 24% 7% 1	506
April	1st to 10th	Day	20% 15% 31% 25% 7% 2	460
	11th to 20th	Day	23% 14% 27% 25% 9% 2	452
	21st to end	Day	23% 13% 32% 22% 9%	460
May	1st to 10th	Day	22% 14% 32% 22% 8% 3	463
	11th to 20th	Day	17% 11% 31% 26% 12% 2	487
	21st to end	Day	19% 16% 32% 25% 8% 1	614
June	1st to 10th	Day	22% 8% 32% 24% 11% 3	680
	11th to 20th	Day	18% 11% 31% 26% 11% 2	680
	21st to end	Day	23% 7% 28% 27% 11% 3	680
July	1st to 10th	Day	15% 9% 32% 31% 12% 3	598
	11th to 20th	Day	16% 7% 31% 28% 13% 4	484
	21st to end	Day	15% 6% 27% 30% 19% 3	532
August	1st to 10th	Day	15% 9% 26% 29% 16% 5%	486
	11th to 20th	Day	17% 5% 23% 32% 15% 8%	479
	21st to end	Day	17% 10% 31% 21% 14% 7%	539
September	1st to 10th	Day	20% 10% 33% 19% 15% 4	490
	11th to 20th	Day	16% 11% 27% 28% 15% 2	490
	21st to end	Day	21% 11% 29% 19% 14% 5%	490
October	1st to 10th	Day	18% 15% 31% 20% 12% 4	490
	11th to 20th	Day	28% 13% 33% 16% 7% 3	417
	21st to end	Day	30% 13% 30% 20% 6% 1	429
November	1st to 10th	Day	28% 17% 32% 18% 5% 1	374
	11th to 20th	Day	25% 15% 30% 22% 5% 1	237
	21st to end	Day	31% 11% 32% 19% 6% 2	180
December	1st to 10th	Day	20% 11% 22% 28% 17% 2	180
	11th to 20th	Day	26% 13% 29% 24% 5% 3	180
	21st to end	Day	25% 14% 28% 23% 8% 2	198
January	1st to 10th	Night	24% 10% 33% 25% 7% 1	760
	11th to 20th	Night	22% 11% 29% 30% 9%	760
	21st to end	Night	14% 9% 28% 37% 12% 1	836
February	1st to 10th	Night	14% 8% 36% 30% 10% 1	760
	11th to 20th	Night	18% 8% 36% 29% 7% 1	743
	21st to end	Night	18% 12% 33% 29% 7% 1	628
March	1st to 10th	Night	19% 11% 32% 30% 7%	760
	11th to 20th	Night	20% 15% 29% 26% 9% 1	760
	21st to end	Night	21% 14% 32% 27% 6%	836
April	1st to 10th	Night	26% 10% 27% 30% 6% 1	760
	11th to 20th	Night	23% 12% 28% 29% 7%	677
	21st to end	Night	24% 13% 33% 25% 5%	570
May	1st to 10th	Night	26% 8% 32% 28% 6%	396
	11th to 20th	Night	21% 9% 34% 25% 10% 1	374
	21st to end	Night	21% 9% 39% 22% 7% 1	411
June	1st to 10th	Night	22% 8% 29% 32% 8% 1	380
	11th to 20th	Night	17% 6% 37% 28% 11% 1	380
	21st to end	Night	18% 7% 26% 37% 10% 2	380
July	1st to 10th	Night	18% 7% 33% 29% 13%	370
	11th to 20th	Night	11% 5% 32% 38% 14%	368
	21st to end	Night	13% 6% 28% 40% 12% 1	416
August	1st to 10th	Night	14% 4 27% 38% 15% 2	378
	11th to 20th	Night	20% 5% 25% 32% 17% 1	456
	21st to end	Night	17% 10% 27% 28% 15% 3	760
September	1st to 10th	Night	19% 8% 30% 31% 11% 1	760
	11th to 20th	Night	20% 9% 31% 27% 12% 2	760
	21st to end	Night	21% 8% 35% 25% 10% 1	760
October	1st to 10th	Night	22% 10% 31% 26% 10% 1	760
	11th to 20th	Night	32% 10% 28% 20% 9% 1	760
	21st to end	Night	32% 12% 28% 21% 7%	836
November	1st to 10th	Night	28% 16% 29% 20% 6% 1	755
	11th to 20th	Night	26% 16% 30% 20% 7%	760
	21st to end	Night	28% 13% 31% 23% 5% 1	849
December	1st to 10th	Night	26% 12% 28% 25% 9% 1	850
	11th to 20th	Night	22% 12% 32% 24% 8% 1	850
	21st to end	Night	25% 12% 27% 27% 7% 1	935

Page generated at 2024-11-01 22:47:47. Version ac07

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