Ste-Anne-des-Lacs
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ste-Anne-des-Lacs clear sky chart from 2005-11-06 to 2024-11-28.

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% 10% 3 8% 5% 5% 5% 4 6% 6% 32%	101773
	Night	16% 11% 4 8% 5% 4 4 3 5% 6% 34%	97782
Transparency	Day	51% 3 12% 22% 11% 1	105223
	Night	51% 3 12% 22% 11% 1	102408
Seeing	Day	23% 16% 32% 20% 7% 2	14586
	Night	22% 13% 31% 25% 8% 1	23573

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	14% 16% 6% 15% 6% 4 4 3 4 4 24%	2517
	11th to 20th	Day	13% 14% 6% 15% 8% 4 4 3 4 5% 25%	2520
	21st to end	Day	11% 16% 7% 11% 6% 5% 6% 4 6% 5% 23%	2772
February	1st to 10th	Day	13% 17% 4 11% 7% 5% 4 4 4 5% 27%	1676
	11th to 20th	Day	11% 17% 4 12% 6% 5% 5% 3 6% 5% 27%	1738
	21st to end	Day	16% 15% 5% 10% 6% 5% 4 3 4 4 27%	1570
March	1st to 10th	Day	18% 15% 4 11% 6% 5% 3 3 4 4 26%	3116
	11th to 20th	Day	11% 18% 5% 12% 6% 4 4 3 4 4 28%	3313
	21st to end	Day	14% 10% 2 8% 4 4 4 3 5% 6% 38%	4148
April	1st to 10th	Day	20% 13% 4 8% 5% 4 3 3 4 5% 32%	2280
	11th to 20th	Day	21% 8% 3 7% 5% 3 4 3 5% 6% 35%	2254
	21st to end	Day	21% 10% 3 8% 5% 4 4 3 5% 5% 32%	2422
May	1st to 10th	Day	20% 10% 3 8% 6% 5% 4 3 5% 6% 30%	4422
	11th to 20th	Day	19% 8% 3 8% 5% 5% 4 3 6% 8% 31%	4398
	21st to end	Day	17% 6% 2 7% 5% 5% 5% 4 6% 7% 36%	4837
June	1st to 10th	Day	21% 6% 3 8% 6% 5% 5% 4 7% 7% 28%	2660
	11th to 20th	Day	15% 7% 2 7% 5% 5% 5% 4 7% 7% 34%	2660
	21st to end	Day	21% 9% 2 8% 5% 6% 5% 4 6% 6% 27%	2660
July	1st to 10th	Day	13% 6% 3 7% 6% 6% 6% 5% 7% 9% 34%	4440
	11th to 20th	Day	15% 5% 2 5% 5% 6% 6% 6% 8% 8% 34%	4440
	21st to end	Day	12% 5% 2 6% 5% 4 5% 4 6% 7% 45%	4814
August	1st to 10th	Day	15% 5% 2 7% 5% 6% 6% 5% 8% 8% 32%	4423
	11th to 20th	Day	15% 6% 3 7% 5% 5% 5% 5% 6% 8% 36%	4019
	21st to end	Day	16% 5% 2 7% 4 4 5% 4 6% 7% 39%	4180
September	1st to 10th	Day	14% 6% 2 6% 4 4 4 4 6% 8% 41%	2280
	11th to 20th	Day	13% 6% 2 6% 3 4 4 3 5% 6% 48%	2216
	21st to end	Day	18% 7% 2 6% 4 4 4 3 5% 7% 41%	2090
October	1st to 10th	Day	21% 7% 3 6% 4 4 4 4 4 7% 36%	1936
	11th to 20th	Day	20% 10% 3 9% 5% 4 4 5% 5% 6% 29%	1871
	21st to end	Day	23% 11% 3 7% 5% 4 4 3 4 6% 29%	1881
November	1st to 10th	Day	14% 10% 3 8% 5% 4 5% 4 6% 7% 34%	1761
	11th to 20th	Day	17% 11% 4 9% 5% 4 4 4 6% 6% 30%	1685
	21st to end	Day	21% 13% 3 9% 4 5% 5% 3 5% 7% 24%	1576
December	1st to 10th	Day	21% 16% 5% 11% 5% 5% 4 3 4 5% 22%	1520
	11th to 20th	Day	19% 15% 4 9% 6% 4 4 3 4 5% 27%	1906
	21st to end	Day	24% 18% 5% 10% 5% 4 3 2 4 4 22%	2772
January	1st to 10th	Night	14% 15% 5% 11% 6% 5% 5% 3 5% 5% 25%	4429
	11th to 20th	Night	10% 13% 6% 14% 7% 5% 4 3 5% 6% 28%	4440
	21st to end	Night	12% 15% 6% 12% 7% 6% 5% 4 5% 6% 25%	4884
February	1st to 10th	Night	12% 13% 5% 11% 7% 6% 5% 4 5% 6% 27%	2501
	11th to 20th	Night	11% 13% 4 11% 6% 4 5% 4 5% 6% 31%	2327
	21st to end	Night	14% 12% 5% 9% 7% 5% 5% 3 5% 5% 31%	1884
March	1st to 10th	Night	18% 13% 4 7% 5% 5% 4 3 4 5% 32%	3724
	11th to 20th	Night	12% 20% 5% 10% 5% 4 4 3 4 5% 29%	3644
	21st to end	Night	13% 8% 4 9% 6% 5% 4 3 4 5% 39%	3482
April	1st to 10th	Night	22% 11% 3 7% 5% 4 3 2 5% 6% 31%	1900
	11th to 20th	Night	19% 6% 3 7% 5% 4 4 4 4 6% 37%	1875
	21st to end	Night	20% 8% 3 7% 4 4 4 3 5% 5% 36%	1757
May	1st to 10th	Night	19% 10% 3 8% 5% 4 5% 4 4 6% 31%	2546
	11th to 20th	Night	21% 8% 3 6% 4 3 3 3 5% 7% 37%	2495
	21st to end	Night	18% 6% 3 7% 5% 5% 5% 4 6% 7% 35%	2738
June	1st to 10th	Night	20% 7% 3 6% 5% 4 4 4 5% 8% 33%	1520
	11th to 20th	Night	18% 7% 2 6% 4 4 5% 3 5% 7% 39%	1520
	21st to end	Night	20% 7% 1 6% 5% 4 4 3 6% 7% 37%	1520
July	1st to 10th	Night	12% 5% 3 7% 6% 5% 6% 5% 7% 7% 37%	2520
	11th to 20th	Night	15% 5% 2 6% 4 4 4 4 5% 8% 44%	2520
	21st to end	Night	11% 5% 1 5% 4 4 5% 4 7% 7% 46%	2739
August	1st to 10th	Night	13% 6% 2 6% 5% 5% 5% 4 6% 8% 40%	2506
	11th to 20th	Night	15% 7% 3 6% 3 4 4 3 5% 7% 43%	2773
	21st to end	Night	17% 5% 2 6% 4 4 4 3 5% 6% 43%	3476
September	1st to 10th	Night	10% 5% 2 6% 4 4 4 4 6% 7% 47%	1900
	11th to 20th	Night	13% 5% 2 5% 3 3 3 3 5% 7% 50%	1963
	21st to end	Night	18% 5% 2 5% 3 3 3 3 5% 6% 46%	2090
October	1st to 10th	Night	17% 7% 3 7% 4 5% 4 3 4 5% 41%	2242
	11th to 20th	Night	19% 8% 2 7% 4 4 4 4 5% 5% 37%	2308
	21st to end	Night	21% 10% 3 7% 5% 4 4 3 5% 7% 32%	2717
November	1st to 10th	Night	16% 10% 3 7% 5% 5% 4 3 6% 7% 32%	2537
	11th to 20th	Night	16% 11% 3 8% 5% 5% 4 4 5% 6% 34%	2714
	21st to end	Night	19% 14% 4 7% 5% 4 4 3 5% 6% 28%	2759
December	1st to 10th	Night	17% 15% 5% 10% 6% 5% 5% 4 5% 6% 22%	2660
	11th to 20th	Night	20% 15% 4 8% 5% 4 4 3 4 5% 27%	3288
	21st to end	Night	24% 18% 4 8% 4 4 3 2 4 4 24%	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	65% 1 11% 16% 6% 1	2518
	11th to 20th	Day	61% 1 11% 18% 8% 1	2520
	21st to end	Day	63% 2 12% 15% 7% 1	2772
February	1st to 10th	Day	60% 2 7% 21% 8% 2	1676
	11th to 20th	Day	59% 2 10% 17% 11% 1	1747
	21st to end	Day	62% 1 8% 15% 10% 3	1570
March	1st to 10th	Day	63% 1 7% 18% 10% 1	3119
	11th to 20th	Day	59% 1 9% 15% 13% 3	3313
	21st to end	Day	49% 1 7% 20% 21% 3	4148
April	1st to 10th	Day	56% 3 7% 19% 13% 3	2280
	11th to 20th	Day	50% 2 7% 23% 15% 2	2254
	21st to end	Day	56% 2 8% 18% 13% 4	2422
May	1st to 10th	Day	56% 1 7% 23% 11% 2	4436
	11th to 20th	Day	52% 2 16% 19% 9% 2	4402
	21st to end	Day	47% 2 10% 25% 15% 1	4837
June	1st to 10th	Day	54% 3 9% 20% 13% 2	2660
	11th to 20th	Day	46% 4 12% 22% 13% 3	2660
	21st to end	Day	56% 3 12% 19% 9% 1	2660
July	1st to 10th	Day	44% 5% 15% 25% 10%	4370
	11th to 20th	Day	42% 5% 17% 29% 8%	4365
	21st to end	Day	37% 4 15% 33% 11%	4661
August	1st to 10th	Day	46% 5% 18% 23% 9%	4409
	11th to 20th	Day	44% 4 16% 29% 6%	4061
	21st to end	Day	42% 4 17% 22% 14% 1	4180
September	1st to 10th	Day	40% 3 14% 30% 14%	2280
	11th to 20th	Day	37% 2 13% 33% 14% 1	2216
	21st to end	Day	43% 3 14% 28% 12%	2090
October	1st to 10th	Day	44% 4 16% 27% 10%	3209
	11th to 20th	Day	45% 3 16% 27% 9%	3087
	21st to end	Day	44% 3 22% 21% 10% 1	3081
November	1st to 10th	Day	50% 3 14% 23% 10% 1	1761
	11th to 20th	Day	54% 3 12% 19% 12% 1	1685
	21st to end	Day	60% 4 13% 16% 6% 1	1576
December	1st to 10th	Day	67% 3 10% 14% 6%	1520
	11th to 20th	Day	60% 2 11% 18% 9%	1906
	21st to end	Day	69% 2 8% 15% 6%	2772
January	1st to 10th	Night	62% 1 15% 15% 6%	4429
	11th to 20th	Night	59% 2 12% 21% 5% 1	4440
	21st to end	Night	63% 2 11% 15% 8% 1	4884
February	1st to 10th	Night	58% 2 8% 21% 9% 1	2501
	11th to 20th	Night	54% 2 10% 22% 11% 1	2329
	21st to end	Night	56% 2 8% 18% 14% 2	1884
March	1st to 10th	Night	57% 1 10% 18% 10% 4	3734
	11th to 20th	Night	60% 1 8% 15% 14% 2	3645
	21st to end	Night	50% 1 5% 22% 16% 4	3482
April	1st to 10th	Night	53% 2 7% 20% 16% 2	1900
	11th to 20th	Night	50% 2 6% 23% 16% 2	1875
	21st to end	Night	50% 3 7% 22% 15% 4	1757
May	1st to 10th	Night	55% 1 10% 22% 9% 3	2552
	11th to 20th	Night	48% 2 13% 21% 13% 2	2496
	21st to end	Night	49% 2 9% 22% 17% 2	2739
June	1st to 10th	Night	49% 3 12% 22% 14% 1	1520
	11th to 20th	Night	45% 4 10% 24% 15% 3	1520
	21st to end	Night	48% 4 13% 21% 14% 1	1520
July	1st to 10th	Night	44% 5% 17% 21% 12% 1	2480
	11th to 20th	Night	38% 4 19% 32% 7%	2472
	21st to end	Night	37% 4 19% 27% 14%	2651
August	1st to 10th	Night	43% 4 15% 29% 9%	2496
	11th to 20th	Night	42% 3 18% 29% 7%	2797
	21st to end	Night	42% 4 15% 24% 14% 1	3476
September	1st to 10th	Night	36% 4 13% 29% 16% 1	1900
	11th to 20th	Night	35% 2 14% 35% 12% 1	1963
	21st to end	Night	39% 3 11% 31% 15%	2090
October	1st to 10th	Night	43% 3 14% 27% 12% 1	3736
	11th to 20th	Night	42% 3 13% 29% 12%	3831
	21st to end	Night	44% 3 20% 19% 13% 2	4467
November	1st to 10th	Night	51% 3 12% 23% 9% 1	2537
	11th to 20th	Night	52% 2 12% 21% 12% 2	2714
	21st to end	Night	57% 3 12% 20% 8% 1	2759
December	1st to 10th	Night	64% 3 10% 18% 5%	2660
	11th to 20th	Night	61% 2 8% 20% 8% 1	3288
	21st to end	Night	67% 1 7% 18% 6%	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	18% 21% 37% 20% 3	180
	11th to 20th	Day	31% 14% 37% 12% 4 1	180
	21st to end	Day	20% 21% 39% 16% 4 1	198
February	1st to 10th	Day	34% 22% 33% 9% 1	254
	11th to 20th	Day	23% 24% 39% 12% 1	345
	21st to end	Day	29% 20% 32% 16% 3	382
March	1st to 10th	Day	28% 18% 32% 17% 4	460
	11th to 20th	Day	25% 23% 32% 15% 3 1	460
	21st to end	Day	29% 22% 27% 15% 5% 1	506
April	1st to 10th	Day	30% 17% 33% 15% 6% 1	460
	11th to 20th	Day	33% 19% 26% 14% 6% 1	452
	21st to end	Day	30% 19% 30% 16% 4 1	460
May	1st to 10th	Day	26% 17% 36% 15% 5% 1	463
	11th to 20th	Day	23% 18% 31% 22% 5% 1	487
	21st to end	Day	23% 20% 31% 20% 6% 1	529
June	1st to 10th	Day	24% 16% 35% 18% 6% 1	490
	11th to 20th	Day	19% 17% 34% 19% 9% 1	490
	21st to end	Day	27% 12% 32% 20% 7% 2	490
July	1st to 10th	Day	13% 12% 36% 26% 10% 2	485
	11th to 20th	Day	16% 11% 36% 27% 9% 1	484
	21st to end	Day	14% 9% 35% 28% 12% 1	532
August	1st to 10th	Day	15% 9% 31% 30% 13% 1	486
	11th to 20th	Day	13% 7% 31% 29% 13% 7%	479
	21st to end	Day	18% 11% 30% 23% 12% 6%	539
September	1st to 10th	Day	18% 7% 36% 23% 11% 5%	490
	11th to 20th	Day	12% 11% 28% 26% 17% 6%	490
	21st to end	Day	22% 12% 27% 22% 12% 5%	490
October	1st to 10th	Day	24% 17% 27% 19% 11% 1	490
	11th to 20th	Day	24% 17% 30% 21% 7% 1	474
	21st to end	Day	31% 15% 31% 18% 4	429
November	1st to 10th	Day	29% 17% 31% 17% 5% 1	395
	11th to 20th	Day	26% 20% 33% 17% 5%	285
	21st to end	Day	29% 19% 34% 14% 4	194
December	1st to 10th	Day	27% 16% 32% 19% 4 1	180
	11th to 20th	Day	30% 21% 37% 10% 2 1	180
	21st to end	Day	36% 21% 25% 13% 5% 1	198
January	1st to 10th	Night	23% 16% 34% 22% 5%	760
	11th to 20th	Night	23% 17% 32% 23% 4	760
	21st to end	Night	16% 15% 39% 24% 6%	836
February	1st to 10th	Night	18% 17% 39% 22% 4 1	760
	11th to 20th	Night	20% 18% 39% 18% 4	743
	21st to end	Night	21% 16% 34% 26% 2	628
March	1st to 10th	Night	23% 17% 33% 24% 3	760
	11th to 20th	Night	24% 16% 34% 19% 6%	760
	21st to end	Night	22% 14% 35% 23% 5%	836
April	1st to 10th	Night	28% 14% 32% 23% 4	760
	11th to 20th	Night	25% 15% 33% 23% 5% 1	751
	21st to end	Night	26% 16% 33% 18% 7%	617
May	1st to 10th	Night	24% 13% 33% 22% 6% 2	399
	11th to 20th	Night	23% 12% 28% 29% 7% 1	374
	21st to end	Night	20% 9% 40% 23% 8%	411
June	1st to 10th	Night	22% 11% 33% 25% 8%	380
	11th to 20th	Night	24% 8% 28% 29% 11%	380
	21st to end	Night	23% 6% 28% 29% 14% 1	380
July	1st to 10th	Night	10% 9% 33% 35% 12% 1	370
	11th to 20th	Night	11% 6% 28% 41% 14%	368
	21st to end	Night	12% 6% 29% 39% 12% 2	416
August	1st to 10th	Night	15% 5% 21% 42% 16% 1	378
	11th to 20th	Night	14% 4 26% 32% 21% 2	549
	21st to end	Night	15% 7% 28% 31% 17% 2	836
September	1st to 10th	Night	13% 7% 31% 37% 12% 1	760
	11th to 20th	Night	15% 7% 25% 31% 20% 1	760
	21st to end	Night	19% 9% 25% 30% 15% 3	760
October	1st to 10th	Night	22% 11% 27% 29% 10% 1	760
	11th to 20th	Night	24% 12% 29% 25% 8% 1	760
	21st to end	Night	27% 12% 32% 24% 5%	836
November	1st to 10th	Night	24% 15% 29% 23% 8% 1	780
	11th to 20th	Night	25% 14% 32% 21% 8% 1	800
	21st to end	Night	29% 17% 28% 20% 5% 1	789
December	1st to 10th	Night	27% 16% 32% 19% 6%	760
	11th to 20th	Night	28% 18% 31% 19% 4 1	760
	21st to end	Night	32% 16% 31% 17% 4	836

Page generated at 2024-11-25 00:22:16. Version ac07

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