Site d'observation de St-Félix d'Otis
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Site d'observation de St-Félix d'Otis clear sky chart from 2005-11-06 to 2024-12-09.

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	17% 12% 4 10% 6% 5% 5% 4 5% 6% 25%	101924
	Night	17% 15% 5% 11% 6% 5% 5% 4 5% 5% 22%	97914
Transparency	Day	57% 8% 13% 16% 6% 1	105362
	Night	62% 7% 11% 14% 5%	102566
Seeing	Day	27% 18% 28% 19% 7% 1	15594
	Night	26% 16% 27% 23% 7% 1	23860

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% 18% 9% 20% 8% 6% 5% 4 4 4 10%	2335
	11th to 20th	Day	10% 13% 7% 18% 16% 7% 8% 5% 6% 4 7%	2520
	21st to end	Day	6% 13% 7% 16% 9% 10% 6% 6% 6% 5% 18%	2772
February	1st to 10th	Day	7% 12% 7% 13% 9% 12% 8% 5% 5% 6% 17%	1520
	11th to 20th	Day	11% 16% 6% 16% 9% 8% 6% 5% 5% 5% 13%	1760
	21st to end	Day	8% 16% 5% 10% 8% 7% 7% 7% 6% 6% 20%	1570
March	1st to 10th	Day	13% 12% 4 9% 5% 5% 6% 4 5% 6% 30%	3116
	11th to 20th	Day	14% 23% 6% 12% 7% 5% 4 3 4 5% 17%	3352
	21st to end	Day	12% 17% 5% 12% 5% 5% 4 3 4 6% 27%	4003
April	1st to 10th	Day	18% 19% 5% 9% 6% 4 3 3 4 6% 23%	2280
	11th to 20th	Day	18% 15% 4 8% 5% 4 4 3 4 5% 30%	2394
	21st to end	Day	19% 14% 4 8% 4 4 4 4 6% 5% 29%	2470
May	1st to 10th	Day	20% 13% 3 7% 4 4 4 3 5% 6% 30%	4249
	11th to 20th	Day	16% 10% 3 7% 5% 5% 5% 4 5% 8% 32%	4398
	21st to end	Day	19% 9% 2 7% 5% 5% 6% 4 6% 7% 29%	5181
June	1st to 10th	Day	22% 9% 3 7% 6% 4 4 4 6% 8% 28%	2850
	11th to 20th	Day	19% 8% 3 8% 5% 5% 5% 4 6% 8% 30%	2850
	21st to end	Day	22% 9% 3 8% 6% 5% 5% 5% 5% 6% 28%	2850
July	1st to 10th	Day	20% 10% 3 7% 4 5% 5% 4 6% 7% 28%	4760
	11th to 20th	Day	15% 8% 4 9% 6% 6% 6% 5% 6% 7% 26%	4516
	21st to end	Day	14% 7% 3 7% 5% 5% 5% 5% 7% 8% 34%	4814
August	1st to 10th	Day	16% 8% 3 7% 6% 5% 6% 5% 8% 9% 28%	4423
	11th to 20th	Day	21% 8% 3 7% 5% 5% 6% 5% 6% 9% 26%	4045
	21st to end	Day	20% 9% 3 8% 4 4 4 3 5% 7% 33%	4450
September	1st to 10th	Day	21% 8% 3 7% 4 6% 4 4 5% 7% 31%	2280
	11th to 20th	Day	21% 8% 3 7% 3 4 4 3 5% 6% 37%	2095
	21st to end	Day	23% 10% 2 7% 4 4 4 4 5% 6% 32%	2090
October	1st to 10th	Day	20% 12% 3 8% 6% 5% 4 4 5% 6% 27%	2076
	11th to 20th	Day	26% 18% 4 9% 5% 5% 4 3 5% 4 17%	1721
	21st to end	Day	24% 23% 5% 8% 4 3 3 2 3 4 20%	1881
November	1st to 10th	Day	20% 20% 6% 11% 5% 4 3 3 4 5% 19%	1761
	11th to 20th	Day	19% 21% 6% 13% 7% 3 4 3 4 5% 17%	1657
	21st to end	Day	17% 23% 7% 15% 7% 6% 3 3 5% 4 11%	1400
December	1st to 10th	Day	16% 22% 6% 17% 9% 6% 4 3 5% 4 8%	1386
	11th to 20th	Day	17% 18% 7% 14% 7% 7% 5% 3 4 3 13%	1668
	21st to end	Day	19% 18% 4 12% 10% 7% 5% 3 4 5% 14%	2431
January	1st to 10th	Night	10% 20% 9% 15% 10% 9% 8% 4 4 3 7%	4611
	11th to 20th	Night	10% 16% 7% 19% 10% 7% 7% 4 4 3 12%	4440
	21st to end	Night	6% 14% 7% 14% 8% 9% 7% 5% 6% 5% 18%	4884
February	1st to 10th	Night	8% 13% 6% 12% 10% 10% 8% 5% 5% 5% 18%	2660
	11th to 20th	Night	11% 16% 7% 16% 9% 7% 6% 5% 4 4 15%	2303
	21st to end	Night	9% 19% 6% 13% 7% 6% 5% 4 5% 4 21%	1884
March	1st to 10th	Night	17% 17% 6% 10% 6% 5% 7% 4 4 5% 21%	3724
	11th to 20th	Night	15% 24% 6% 13% 6% 5% 4 3 3 5% 16%	3607
	21st to end	Night	14% 16% 5% 12% 5% 4 4 3 6% 6% 27%	3626
April	1st to 10th	Night	20% 18% 4 10% 5% 4 4 3 4 4 25%	1900
	11th to 20th	Night	21% 13% 4 7% 4 5% 3 3 4 6% 29%	1735
	21st to end	Night	21% 12% 3 6% 4 4 4 3 5% 5% 33%	1710
May	1st to 10th	Night	21% 13% 3 6% 4 5% 4 3 5% 5% 29%	2720
	11th to 20th	Night	18% 9% 2 7% 4 4 3 3 5% 6% 37%	2495
	21st to end	Night	23% 7% 3 6% 5% 6% 4 4 6% 8% 28%	2405
June	1st to 10th	Night	19% 9% 3 9% 6% 5% 5% 4 6% 6% 28%	1330
	11th to 20th	Night	19% 8% 3 6% 5% 5% 6% 4 4 7% 34%	1330
	21st to end	Night	21% 8% 3 8% 7% 5% 6% 3 6% 8% 27%	1330
July	1st to 10th	Night	20% 9% 3 8% 6% 5% 5% 4 6% 6% 29%	2210
	11th to 20th	Night	15% 8% 2 8% 6% 5% 6% 6% 7% 7% 29%	2443
	21st to end	Night	15% 6% 3 7% 5% 4 6% 5% 6% 8% 35%	2739
August	1st to 10th	Night	17% 8% 3 8% 6% 6% 5% 5% 7% 9% 29%	2506
	11th to 20th	Night	19% 9% 3 8% 7% 6% 6% 4 6% 7% 25%	2751
	21st to end	Night	18% 9% 3 7% 4 5% 5% 4 5% 7% 33%	3203
September	1st to 10th	Night	21% 8% 3 7% 5% 4 4 4 6% 5% 33%	1900
	11th to 20th	Night	22% 7% 3 7% 5% 5% 5% 4 5% 5% 34%	2084
	21st to end	Night	22% 9% 3 6% 4 4 4 3 4 6% 35%	2090
October	1st to 10th	Night	21% 11% 2 7% 5% 4 3 3 6% 7% 32%	2103
	11th to 20th	Night	29% 17% 4 7% 5% 4 4 3 4 4 21%	2456
	21st to end	Night	26% 18% 5% 7% 4 4 4 3 4 5% 19%	2717
November	1st to 10th	Night	24% 20% 6% 9% 4 3 4 2 4 5% 19%	2537
	11th to 20th	Night	18% 21% 7% 11% 6% 4 3 3 4 4 17%	2737
	21st to end	Night	18% 22% 7% 15% 9% 4 4 4 3 3 11%	3000
December	1st to 10th	Night	18% 20% 7% 16% 9% 6% 4 3 4 4 9%	2977
	11th to 20th	Night	18% 18% 6% 15% 8% 7% 6% 4 3 4 11%	3531
	21st to end	Night	16% 21% 6% 14% 8% 6% 5% 3 3 2 17%	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	72% 9% 10% 8% 1	2336
	11th to 20th	Day	76% 6% 8% 7% 3 1	2520
	21st to end	Day	62% 9% 9% 11% 9%	2772
February	1st to 10th	Day	64% 8% 12% 10% 6% 1	1520
	11th to 20th	Day	69% 6% 12% 8% 5%	1768
	21st to end	Day	61% 7% 11% 14% 6% 1	1570
March	1st to 10th	Day	53% 8% 16% 16% 6% 2	3119
	11th to 20th	Day	69% 7% 10% 10% 5%	3352
	21st to end	Day	58% 6% 12% 15% 7% 2	4003
April	1st to 10th	Day	64% 5% 9% 13% 6% 2	2280
	11th to 20th	Day	56% 5% 12% 18% 8% 1	2394
	21st to end	Day	55% 7% 11% 15% 11% 1	2470
May	1st to 10th	Day	51% 8% 15% 15% 10% 1	4263
	11th to 20th	Day	47% 9% 14% 23% 6%	4402
	21st to end	Day	50% 9% 12% 20% 9%	5181
June	1st to 10th	Day	54% 8% 10% 17% 10% 1	2850
	11th to 20th	Day	51% 7% 14% 18% 9% 1	2850
	21st to end	Day	56% 8% 12% 16% 8%	2850
July	1st to 10th	Day	52% 7% 13% 25% 3	4685
	11th to 20th	Day	53% 9% 19% 16% 3	4438
	21st to end	Day	46% 9% 19% 21% 5%	4661
August	1st to 10th	Day	49% 10% 18% 20% 3	4409
	11th to 20th	Day	54% 9% 21% 13% 3	4084
	21st to end	Day	52% 7% 16% 17% 8%	4450
September	1st to 10th	Day	51% 8% 15% 20% 6%	2280
	11th to 20th	Day	47% 7% 17% 22% 6%	2095
	21st to end	Day	53% 9% 13% 18% 6%	2090
October	1st to 10th	Day	60% 7% 10% 18% 4	3453
	11th to 20th	Day	68% 7% 11% 14% 1	2833
	21st to end	Day	64% 5% 15% 14% 2	3081
November	1st to 10th	Day	68% 6% 13% 10% 3	1761
	11th to 20th	Day	71% 9% 8% 9% 3	1657
	21st to end	Day	76% 9% 10% 5% 1	1400
December	1st to 10th	Day	79% 7% 7% 6% 1	1386
	11th to 20th	Day	73% 5% 10% 9% 3	1668
	21st to end	Day	69% 7% 10% 9% 4	2431
January	1st to 10th	Night	77% 8% 8% 6% 1	4611
	11th to 20th	Night	72% 6% 9% 10% 3	4440
	21st to end	Night	62% 8% 10% 12% 7%	4884
February	1st to 10th	Night	63% 7% 12% 12% 6%	2660
	11th to 20th	Night	69% 6% 11% 10% 4	2306
	21st to end	Night	64% 5% 9% 15% 6%	1884
March	1st to 10th	Night	64% 8% 10% 13% 5%	3734
	11th to 20th	Night	71% 6% 9% 9% 4	3608
	21st to end	Night	57% 7% 10% 17% 7% 1	3626
April	1st to 10th	Night	64% 4 9% 13% 8% 2	1900
	11th to 20th	Night	56% 6% 8% 18% 12% 1	1735
	21st to end	Night	52% 5% 11% 21% 10% 2	1710
May	1st to 10th	Night	52% 8% 14% 15% 10% 1	2726
	11th to 20th	Night	46% 8% 13% 22% 10% 1	2496
	21st to end	Night	51% 8% 11% 19% 11% 1	2406
June	1st to 10th	Night	54% 8% 11% 19% 6% 2	1330
	11th to 20th	Night	48% 7% 12% 18% 11% 3	1330
	21st to end	Night	54% 9% 13% 17% 7%	1330
July	1st to 10th	Night	53% 7% 13% 22% 5%	2175
	11th to 20th	Night	49% 10% 18% 20% 3	2398
	21st to end	Night	44% 10% 19% 19% 8%	2651
August	1st to 10th	Night	49% 10% 19% 17% 4	2496
	11th to 20th	Night	55% 11% 19% 12% 3	2778
	21st to end	Night	49% 8% 12% 25% 5% 1	3203
September	1st to 10th	Night	49% 8% 14% 21% 9%	1900
	11th to 20th	Night	51% 9% 15% 18% 6%	2084
	21st to end	Night	51% 8% 12% 22% 7% 1	2090
October	1st to 10th	Night	53% 7% 11% 23% 5% 1	3506
	11th to 20th	Night	65% 5% 11% 16% 3	4083
	21st to end	Night	65% 5% 14% 13% 2	4467
November	1st to 10th	Night	67% 7% 10% 11% 4	2537
	11th to 20th	Night	69% 8% 10% 10% 3	2737
	21st to end	Night	77% 8% 8% 5% 2	3000
December	1st to 10th	Night	79% 7% 7% 5% 1	2977
	11th to 20th	Night	76% 7% 7% 7% 3	3532
	21st to end	Night	71% 7% 9% 10% 3	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	23% 27% 31% 17% 2	180
	11th to 20th	Day	21% 27% 32% 16% 3 1	180
	21st to end	Day	17% 25% 34% 18% 5% 1	198
February	1st to 10th	Day	19% 27% 39% 11% 3 1	180
	11th to 20th	Day	25% 26% 32% 14% 4	407
	21st to end	Day	27% 24% 27% 17% 4 1	382
March	1st to 10th	Day	27% 21% 32% 15% 4	460
	11th to 20th	Day	31% 21% 26% 15% 6% 1	460
	21st to end	Day	33% 20% 26% 15% 6% 1	506
April	1st to 10th	Day	33% 22% 28% 13% 3 1	460
	11th to 20th	Day	30% 19% 32% 14% 5% 1	452
	21st to end	Day	26% 22% 30% 17% 4 1	460
May	1st to 10th	Day	31% 20% 27% 15% 6% 1	463
	11th to 20th	Day	20% 17% 35% 20% 7% 1	487
	21st to end	Day	29% 16% 26% 20% 8% 1	730
June	1st to 10th	Day	27% 14% 29% 24% 5% 1	680
	11th to 20th	Day	24% 15% 25% 24% 11% 1	680
	21st to end	Day	25% 15% 27% 23% 9% 1	680
July	1st to 10th	Day	23% 14% 27% 26% 8% 1	670
	11th to 20th	Day	23% 11% 29% 26% 9% 2	531
	21st to end	Day	20% 13% 32% 23% 11% 2	532
August	1st to 10th	Day	24% 12% 27% 25% 9% 3	486
	11th to 20th	Day	22% 10% 29% 26% 10% 3	479
	21st to end	Day	28% 12% 24% 22% 12% 3	539
September	1st to 10th	Day	26% 18% 25% 18% 10% 4	490
	11th to 20th	Day	23% 16% 30% 18% 10% 2	490
	21st to end	Day	27% 16% 25% 20% 10% 2	490
October	1st to 10th	Day	26% 18% 28% 17% 8% 3	483
	11th to 20th	Day	38% 19% 22% 13% 8% 1	390
	21st to end	Day	40% 18% 24% 15% 3	429
November	1st to 10th	Day	39% 19% 22% 16% 3 1	395
	11th to 20th	Day	30% 23% 26% 13% 6% 1	371
	21st to end	Day	41% 23% 25% 10% 3	200
December	1st to 10th	Day	26% 24% 32% 14% 3 1	196
	11th to 20th	Day	32% 26% 32% 8% 3 1	180
	21st to end	Day	33% 26% 25% 10% 6% 1	198
January	1st to 10th	Night	25% 22% 31% 18% 4	810
	11th to 20th	Night	22% 22% 30% 19% 5% 1	760
	21st to end	Night	17% 18% 36% 22% 6% 1	836
February	1st to 10th	Night	16% 23% 32% 22% 6% 1	760
	11th to 20th	Night	23% 24% 31% 17% 6%	743
	21st to end	Night	24% 18% 33% 19% 5% 1	628
March	1st to 10th	Night	23% 17% 34% 23% 4	760
	11th to 20th	Night	26% 21% 29% 16% 8% 1	760
	21st to end	Night	26% 19% 27% 23% 5% 1	836
April	1st to 10th	Night	32% 16% 28% 20% 5% 1	760
	11th to 20th	Night	28% 14% 28% 23% 6%	611
	21st to end	Night	30% 13% 28% 24% 5%	570
May	1st to 10th	Night	30% 9% 30% 27% 5%	508
	11th to 20th	Night	21% 9% 27% 33% 10%	374
	21st to end	Night	28% 12% 27% 26% 7%	411
June	1st to 10th	Night	21% 9% 31% 31% 8% 1	380
	11th to 20th	Night	21% 8% 23% 34% 14% 1	380
	21st to end	Night	20% 9% 26% 34% 10% 1	380
July	1st to 10th	Night	23% 8% 27% 32% 9% 1	370
	11th to 20th	Night	15% 10% 23% 41% 11% 1	368
	21st to end	Night	24% 7% 21% 36% 11% 1	416
August	1st to 10th	Night	16% 8% 21% 40% 15% 1	378
	11th to 20th	Night	22% 9% 21% 29% 17% 1	543
	21st to end	Night	23% 10% 24% 29% 13% 1	667
September	1st to 10th	Night	24% 13% 24% 27% 11% 1	760
	11th to 20th	Night	27% 9% 25% 25% 12% 3	760
	21st to end	Night	25% 13% 24% 26% 11% 1	760
October	1st to 10th	Night	28% 13% 25% 25% 8% 1	760
	11th to 20th	Night	39% 14% 21% 17% 8% 1	760
	21st to end	Night	37% 17% 23% 18% 5%	836
November	1st to 10th	Night	34% 18% 24% 18% 5% 1	780
	11th to 20th	Night	29% 23% 24% 17% 6% 1	857
	21st to end	Night	31% 21% 28% 15% 4 1	900
December	1st to 10th	Night	28% 20% 29% 17% 5% 1	893
	11th to 20th	Night	30% 20% 27% 16% 6%	850
	21st to end	Night	29% 20% 27% 18% 6% 1	935

Page generated at 2024-12-06 03:54:52. Version ac07

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