Pointe-au-Chêne
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pointe-au-Chêne clear sky chart from 2005-11-06 to 2024-11-08.

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	18% 10% 3 8% 5% 4 4 4 5% 6% 31%	101579
	Night	19% 11% 4 8% 5% 4 4 3 5% 6% 32%	97525
Transparency	Day	28% 47% 7% 12% 5%	105039
	Night	29% 47% 7% 11% 5% 1	102154
Seeing	Day	26% 15% 30% 19% 8% 2	14520
	Night	25% 11% 29% 26% 9% 1	23525

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% 20% 6% 14% 6% 4 4 2 4 4 19%	2517
	11th to 20th	Day	16% 15% 7% 14% 7% 5% 3 2 5% 5% 21%	2520
	21st to end	Day	14% 20% 8% 10% 5% 6% 6% 4 4 4 19%	2776
February	1st to 10th	Day	14% 17% 5% 13% 6% 5% 3 3 4 6% 25%	1710
	11th to 20th	Day	13% 17% 5% 11% 6% 4 4 3 5% 5% 25%	1712
	21st to end	Day	20% 16% 5% 8% 6% 5% 4 3 4 4 25%	1570
March	1st to 10th	Day	20% 15% 4 10% 5% 4 4 3 4 5% 26%	3116
	11th to 20th	Day	13% 19% 5% 11% 6% 4 4 4 4 4 26%	3374
	21st to end	Day	16% 8% 3 7% 5% 4 5% 3 5% 6% 37%	4097
April	1st to 10th	Day	21% 15% 3 7% 4 4 4 2 4 5% 31%	2280
	11th to 20th	Day	23% 10% 3 6% 4 5% 3 3 4 5% 35%	2254
	21st to end	Day	23% 10% 3 7% 5% 4 4 3 5% 5% 31%	2416
May	1st to 10th	Day	21% 9% 3 8% 5% 5% 5% 4 5% 6% 29%	4426
	11th to 20th	Day	20% 8% 3 6% 5% 4 4 4 6% 7% 33%	4398
	21st to end	Day	18% 7% 2 7% 5% 4 5% 4 5% 7% 36%	4837
June	1st to 10th	Day	24% 8% 3 7% 6% 4 4 3 6% 7% 29%	2660
	11th to 20th	Day	16% 7% 3 7% 5% 6% 4 5% 6% 7% 35%	2660
	21st to end	Day	23% 6% 3 7% 6% 5% 4 4 6% 8% 28%	2660
July	1st to 10th	Day	14% 7% 3 7% 5% 5% 6% 5% 7% 9% 33%	4440
	11th to 20th	Day	16% 6% 2 6% 5% 5% 6% 4 7% 8% 34%	4440
	21st to end	Day	12% 6% 2 6% 4 4 4 4 6% 7% 45%	4814
August	1st to 10th	Day	16% 6% 3 8% 6% 6% 5% 5% 6% 8% 32%	4423
	11th to 20th	Day	16% 7% 3 6% 4 4 4 4 6% 8% 37%	3983
	21st to end	Day	17% 5% 2 6% 4 4 5% 4 5% 9% 38%	4180
September	1st to 10th	Day	17% 6% 2 5% 4 4 4 4 5% 7% 42%	2280
	11th to 20th	Day	15% 4 1 5% 3 3 4 3 6% 6% 48%	2239
	21st to end	Day	20% 6% 2 5% 3 4 4 3 5% 7% 40%	2090
October	1st to 10th	Day	23% 8% 2 7% 4 3 5% 3 4 7% 34%	1900
	11th to 20th	Day	25% 10% 4 8% 4 4 4 3 4 6% 28%	1900
	21st to end	Day	25% 11% 4 8% 5% 4 3 3 4 6% 27%	1881
November	1st to 10th	Day	18% 11% 3 6% 5% 5% 4 3 5% 7% 33%	1734
	11th to 20th	Day	22% 12% 4 9% 5% 5% 5% 4 5% 6% 24%	1574
	21st to end	Day	23% 15% 4 9% 5% 4 4 4 3 5% 24%	1520
December	1st to 10th	Day	23% 20% 5% 9% 5% 4 4 3 4 5% 18%	1520
	11th to 20th	Day	22% 16% 5% 10% 5% 4 4 3 4 5% 24%	1906
	21st to end	Day	26% 21% 4 9% 4 4 3 2 3 3 19%	2772
January	1st to 10th	Night	18% 19% 6% 11% 4 4 4 3 4 5% 22%	4429
	11th to 20th	Night	13% 17% 5% 14% 6% 5% 5% 3 4 5% 21%	4440
	21st to end	Night	15% 18% 7% 12% 6% 6% 4 3 4 5% 21%	4875
February	1st to 10th	Night	15% 15% 5% 11% 6% 5% 4 4 5% 5% 25%	2470
	11th to 20th	Night	15% 13% 5% 12% 8% 5% 3 3 4 5% 27%	2353
	21st to end	Night	17% 14% 5% 9% 5% 5% 3 4 4 6% 29%	1884
March	1st to 10th	Night	21% 13% 4 8% 4 4 3 3 4 4 32%	3724
	11th to 20th	Night	18% 19% 4 8% 4 4 3 3 4 5% 28%	3580
	21st to end	Night	16% 10% 4 8% 5% 5% 4 3 4 4 38%	3535
April	1st to 10th	Night	23% 10% 3 6% 5% 4 4 3 4 5% 33%	1900
	11th to 20th	Night	22% 8% 3 6% 5% 3 4 3 4 6% 35%	1875
	21st to end	Night	22% 10% 3 6% 4 3 5% 3 4 4 35%	1782
May	1st to 10th	Night	20% 9% 3 7% 5% 5% 5% 4 6% 6% 31%	2514
	11th to 20th	Night	22% 7% 2 6% 3 4 4 3 5% 6% 39%	2495
	21st to end	Night	20% 7% 2 6% 5% 4 5% 4 6% 6% 36%	2738
June	1st to 10th	Night	20% 6% 2 7% 5% 5% 4 4 7% 9% 31%	1520
	11th to 20th	Night	16% 6% 3 7% 4 4 4 5% 5% 6% 40%	1520
	21st to end	Night	21% 6% 2 7% 4 4 4 4 6% 6% 35%	1520
July	1st to 10th	Night	14% 8% 2 8% 5% 5% 5% 4 6% 6% 36%	2520
	11th to 20th	Night	16% 7% 2 6% 3 4 3 3 6% 7% 41%	2520
	21st to end	Night	13% 5% 2 5% 5% 4 4 4 6% 7% 45%	2739
August	1st to 10th	Night	15% 6% 3 7% 5% 4 5% 4 6% 8% 38%	2506
	11th to 20th	Night	18% 6% 1 6% 4 4 4 3 6% 6% 42%	2809
	21st to end	Night	17% 5% 2 6% 4 5% 4 3 5% 6% 43%	3476
September	1st to 10th	Night	14% 5% 2 7% 4 4 4 3 5% 7% 45%	1900
	11th to 20th	Night	17% 5% 1 5% 3 3 3 3 6% 6% 49%	1940
	21st to end	Night	19% 6% 2 4 3 4 4 3 5% 7% 44%	2090
October	1st to 10th	Night	20% 7% 3 6% 4 4 5% 3 5% 6% 38%	2276
	11th to 20th	Night	23% 9% 3 7% 5% 4 4 3 4 6% 33%	2280
	21st to end	Night	25% 10% 3 8% 5% 4 3 3 3 5% 30%	2715
November	1st to 10th	Night	22% 11% 3 7% 4 3 4 3 4 6% 32%	2505
	11th to 20th	Night	19% 12% 4 7% 6% 4 4 3 4 5% 30%	2603
	21st to end	Night	23% 15% 5% 8% 5% 4 4 3 4 5% 24%	2660
December	1st to 10th	Night	22% 18% 6% 10% 6% 4 4 4 4 5% 19%	2660
	11th to 20th	Night	24% 16% 4 9% 4 4 3 3 3 5% 25%	3288
	21st to end	Night	28% 19% 4 10% 4 3 3 3 4 3 20%	4884

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	43% 40% 6% 5% 4 1	2518
	11th to 20th	Day	40% 40% 9% 9% 3	2520
	21st to end	Day	45% 42% 6% 5% 2	2776
February	1st to 10th	Day	24% 64% 3 7% 2 1	1710
	11th to 20th	Day	22% 64% 3 7% 5%	1721
	21st to end	Day	22% 65% 3 4 5% 1	1570
March	1st to 10th	Day	38% 42% 3 10% 6%	3119
	11th to 20th	Day	38% 41% 6% 6% 7% 2	3374
	21st to end	Day	27% 40% 5% 13% 13% 1	4097
April	1st to 10th	Day	20% 64% 3 6% 6% 1	2280
	11th to 20th	Day	20% 65% 2 8% 5% 1	2254
	21st to end	Day	21% 64% 3 6% 5%	2416
May	1st to 10th	Day	34% 43% 5% 15% 3	4440
	11th to 20th	Day	31% 44% 11% 10% 4	4402
	21st to end	Day	29% 41% 7% 14% 8%	4837
June	1st to 10th	Day	19% 64% 2 9% 5% 1	2660
	11th to 20th	Day	17% 65% 4 7% 6% 1	2660
	21st to end	Day	19% 63% 3 10% 4	2660
July	1st to 10th	Day	31% 37% 10% 15% 6%	4370
	11th to 20th	Day	29% 37% 11% 20% 3	4365
	21st to end	Day	23% 36% 10% 25% 7%	4661
August	1st to 10th	Day	32% 38% 11% 14% 5%	4409
	11th to 20th	Day	30% 38% 10% 20% 3	4024
	21st to end	Day	27% 38% 12% 15% 8%	4180
September	1st to 10th	Day	17% 60% 6% 11% 6%	2280
	11th to 20th	Day	13% 60% 6% 14% 5% 1	2239
	21st to end	Day	14% 60% 6% 13% 7%	2090
October	1st to 10th	Day	30% 37% 8% 20% 4	3160
	11th to 20th	Day	26% 39% 11% 20% 4	3140
	21st to end	Day	28% 38% 16% 14% 4	3081
November	1st to 10th	Day	27% 57% 5% 7% 3 1	1734
	11th to 20th	Day	23% 60% 4 8% 4	1574
	21st to end	Day	26% 61% 5% 5% 3	1520
December	1st to 10th	Day	28% 61% 3 6% 2	1520
	11th to 20th	Day	35% 49% 7% 6% 3	1906
	21st to end	Day	45% 38% 3 10% 4	2772
January	1st to 10th	Night	40% 39% 12% 7% 2	4429
	11th to 20th	Night	38% 41% 11% 8% 2	4440
	21st to end	Night	45% 41% 6% 5% 2	4875
February	1st to 10th	Night	22% 65% 3 8% 2	2470
	11th to 20th	Night	21% 63% 3 8% 5%	2355
	21st to end	Night	20% 64% 3 6% 7%	1884
March	1st to 10th	Night	33% 41% 6% 11% 7% 3	3734
	11th to 20th	Night	36% 42% 5% 8% 7% 1	3581
	21st to end	Night	30% 40% 4 14% 10% 2	3535
April	1st to 10th	Night	20% 64% 2 7% 6%	1900
	11th to 20th	Night	20% 65% 2 8% 5%	1875
	21st to end	Night	18% 64% 4 7% 6% 1	1782
May	1st to 10th	Night	32% 44% 7% 13% 3	2520
	11th to 20th	Night	30% 44% 8% 12% 6%	2496
	21st to end	Night	31% 41% 6% 13% 9%	2739
June	1st to 10th	Night	17% 65% 4 9% 6%	1520
	11th to 20th	Night	14% 65% 3 9% 7% 1	1520
	21st to end	Night	18% 63% 3 9% 6%	1520
July	1st to 10th	Night	35% 36% 11% 11% 7% 1	2480
	11th to 20th	Night	28% 36% 12% 21% 3	2472
	21st to end	Night	23% 36% 12% 19% 9%	2651
August	1st to 10th	Night	30% 37% 9% 19% 5%	2496
	11th to 20th	Night	30% 37% 12% 18% 3	2834
	21st to end	Night	28% 37% 10% 15% 8% 2	3476
September	1st to 10th	Night	14% 60% 6% 12% 8%	1900
	11th to 20th	Night	13% 60% 6% 15% 5% 1	1940
	21st to end	Night	14% 59% 6% 14% 7%	2090
October	1st to 10th	Night	26% 37% 10% 20% 6%	3796
	11th to 20th	Night	25% 38% 9% 21% 7%	3779
	21st to end	Night	29% 37% 13% 13% 8%	4465
November	1st to 10th	Night	27% 56% 5% 8% 4	2505
	11th to 20th	Night	23% 59% 5% 9% 4	2603
	21st to end	Night	26% 60% 5% 7% 3	2660
December	1st to 10th	Night	28% 59% 4 7% 2	2660
	11th to 20th	Night	34% 49% 4 8% 4 1	3288
	21st to end	Night	46% 38% 3 10% 3	4884

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	31% 18% 32% 16% 4	180
	11th to 20th	Day	32% 18% 36% 8% 7%	180
	21st to end	Day	25% 17% 35% 20% 4 1	200
February	1st to 10th	Day	33% 25% 33% 7% 2	270
	11th to 20th	Day	27% 28% 35% 10%	319
	21st to end	Day	33% 19% 29% 16% 2	382
March	1st to 10th	Day	30% 17% 32% 18% 2	460
	11th to 20th	Day	29% 20% 33% 13% 4 1	460
	21st to end	Day	32% 20% 26% 15% 5% 1	506
April	1st to 10th	Day	31% 19% 29% 15% 6% 1	460
	11th to 20th	Day	35% 17% 23% 15% 8% 1	452
	21st to end	Day	34% 18% 31% 10% 6% 1	460
May	1st to 10th	Day	28% 16% 35% 15% 5% 2	463
	11th to 20th	Day	21% 19% 30% 22% 7% 1	487
	21st to end	Day	23% 16% 33% 20% 6% 1	529
June	1st to 10th	Day	27% 11% 35% 20% 7% 1	490
	11th to 20th	Day	17% 14% 34% 21% 10% 3	490
	21st to end	Day	28% 11% 31% 19% 9% 2	490
July	1st to 10th	Day	16% 9% 35% 25% 12% 4	485
	11th to 20th	Day	16% 11% 35% 24% 12% 2	484
	21st to end	Day	17% 9% 32% 29% 11% 3	532
August	1st to 10th	Day	17% 8% 28% 33% 11% 2	486
	11th to 20th	Day	19% 5% 25% 31% 14% 6%	479
	21st to end	Day	18% 12% 26% 24% 14% 6%	539
September	1st to 10th	Day	20% 10% 30% 22% 14% 4	490
	11th to 20th	Day	16% 7% 26% 21% 20% 9%	490
	21st to end	Day	22% 12% 26% 21% 13% 5%	490
October	1st to 10th	Day	27% 14% 23% 22% 11% 3	490
	11th to 20th	Day	28% 18% 27% 19% 7% 1	490
	21st to end	Day	33% 14% 30% 19% 3	429
November	1st to 10th	Day	33% 13% 28% 20% 5% 1	386
	11th to 20th	Day	28% 20% 35% 10% 6%	234
	21st to end	Day	32% 21% 29% 15% 3	180
December	1st to 10th	Day	35% 11% 36% 15% 3 1	180
	11th to 20th	Day	31% 25% 33% 9% 3	180
	21st to end	Day	35% 19% 30% 12% 3 1	198
January	1st to 10th	Night	30% 13% 34% 20% 4	760
	11th to 20th	Night	29% 16% 30% 19% 5% 1	760
	21st to end	Night	19% 16% 35% 23% 6% 1	836
February	1st to 10th	Night	23% 16% 33% 23% 4	760
	11th to 20th	Night	23% 19% 34% 21% 4	743
	21st to end	Night	25% 16% 32% 23% 3	628
March	1st to 10th	Night	25% 15% 32% 23% 5%	760
	11th to 20th	Night	27% 18% 30% 19% 4	760
	21st to end	Night	24% 14% 31% 24% 7%	836
April	1st to 10th	Night	29% 14% 29% 24% 4	760
	11th to 20th	Night	26% 14% 31% 21% 6%	751
	21st to end	Night	29% 13% 30% 21% 7%	642
May	1st to 10th	Night	24% 10% 31% 26% 7% 2	380
	11th to 20th	Night	23% 9% 29% 30% 9% 1	374
	21st to end	Night	21% 7% 34% 27% 10% 1	411
June	1st to 10th	Night	21% 6% 29% 33% 11%	380
	11th to 20th	Night	20% 7% 26% 34% 12% 1	380
	21st to end	Night	23% 4 27% 31% 14% 1	380
July	1st to 10th	Night	12% 6% 27% 36% 18%	370
	11th to 20th	Night	14% 3 22% 43% 17% 1	368
	21st to end	Night	15% 3 25% 39% 17% 1	416
August	1st to 10th	Night	15% 4 17% 44% 20% 1	378
	11th to 20th	Night	16% 3 19% 35% 25% 2	573
	21st to end	Night	18% 4 22% 35% 18% 2	836
September	1st to 10th	Night	17% 6% 28% 34% 15% 1	760
	11th to 20th	Night	21% 4 19% 30% 24% 3	760
	21st to end	Night	23% 8% 22% 29% 16% 3	760
October	1st to 10th	Night	24% 8% 26% 28% 13%	760
	11th to 20th	Night	27% 10% 28% 27% 7% 1	760
	21st to end	Night	30% 11% 29% 25% 5%	836
November	1st to 10th	Night	29% 11% 28% 24% 8% 1	771
	11th to 20th	Night	26% 15% 31% 18% 9% 1	760
	21st to end	Night	31% 14% 29% 18% 7%	760
December	1st to 10th	Night	31% 15% 31% 19% 4	760
	11th to 20th	Night	30% 17% 29% 18% 5% 1	760
	21st to end	Night	37% 14% 28% 17% 4	836

Page generated at 2024-11-05 08:15:54. Version ac07

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