Dolbeau-Mistassini
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dolbeau-Mistassini clear sky chart from 2005-11-06 to 2024-12-06.

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	16% 10% 4 9% 6% 5% 5% 4 6% 7% 28%	101897
	Night	16% 12% 4 10% 6% 5% 5% 4 5% 6% 26%	97838
Transparency	Day	56% 3 12% 20% 8% 1	105317
	Night	60% 3 11% 19% 7% 1	102495
Seeing	Day	23% 8% 26% 26% 13% 4	15303
	Night	24% 6% 26% 31% 11% 1	23704

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	13% 18% 8% 15% 7% 5% 5% 3 4 4 15%	2438
	11th to 20th	Day	12% 12% 5% 17% 8% 9% 6% 5% 7% 5% 14%	2520
	21st to end	Day	8% 14% 5% 14% 6% 5% 4 4 6% 6% 27%	2772
February	1st to 10th	Day	8% 13% 5% 10% 9% 7% 8% 5% 6% 5% 24%	1520
	11th to 20th	Day	11% 14% 5% 13% 9% 6% 6% 4 5% 6% 21%	1734
	21st to end	Day	11% 14% 4 11% 6% 5% 6% 5% 7% 6% 24%	1570
March	1st to 10th	Day	17% 13% 4 8% 5% 4 3 3 5% 6% 32%	3116
	11th to 20th	Day	14% 17% 4 10% 6% 6% 5% 5% 5% 6% 21%	3251
	21st to end	Day	11% 10% 5% 11% 6% 5% 5% 4 6% 7% 30%	4152
April	1st to 10th	Day	17% 14% 4 11% 7% 4 4 3 5% 5% 26%	2280
	11th to 20th	Day	18% 9% 3 8% 5% 5% 5% 3 6% 6% 33%	2342
	21st to end	Day	20% 10% 4 8% 4 5% 4 3 5% 6% 32%	2470
May	1st to 10th	Day	17% 10% 3 8% 5% 5% 6% 4 6% 7% 30%	4424
	11th to 20th	Day	17% 8% 3 8% 5% 5% 4 3 6% 7% 35%	4398
	21st to end	Day	15% 8% 3 7% 5% 5% 5% 4 7% 8% 33%	5054
June	1st to 10th	Day	20% 8% 3 8% 5% 5% 5% 4 6% 7% 29%	2850
	11th to 20th	Day	16% 7% 3 7% 5% 4 5% 5% 8% 7% 33%	2850
	21st to end	Day	22% 8% 2 6% 6% 5% 5% 3 6% 8% 28%	2850
July	1st to 10th	Day	16% 8% 3 7% 5% 6% 6% 5% 7% 8% 29%	4706
	11th to 20th	Day	15% 7% 3 7% 5% 6% 6% 5% 7% 9% 31%	4440
	21st to end	Day	13% 7% 3 7% 6% 5% 5% 5% 7% 9% 35%	4814
August	1st to 10th	Day	15% 6% 3 9% 5% 6% 7% 6% 7% 10% 26%	4423
	11th to 20th	Day	15% 7% 4 9% 6% 6% 6% 5% 7% 10% 27%	4180
	21st to end	Day	15% 7% 3 9% 6% 5% 6% 4 6% 7% 33%	4323
September	1st to 10th	Day	17% 7% 2 9% 5% 5% 5% 4 6% 7% 32%	2280
	11th to 20th	Day	17% 7% 3 7% 4 5% 5% 3 6% 8% 34%	2157
	21st to end	Day	23% 8% 2 8% 5% 5% 5% 4 5% 6% 30%	2090
October	1st to 10th	Day	19% 9% 3 8% 5% 5% 5% 4 5% 6% 31%	2010
	11th to 20th	Day	27% 12% 4 10% 5% 5% 5% 4 4 6% 18%	1752
	21st to end	Day	26% 14% 4 7% 5% 5% 4 3 5% 6% 22%	1881
November	1st to 10th	Day	20% 15% 4 10% 6% 5% 5% 4 4 5% 22%	1761
	11th to 20th	Day	21% 13% 6% 10% 7% 5% 5% 3 5% 5% 20%	1625
	21st to end	Day	23% 18% 6% 11% 5% 5% 4 4 4 6% 15%	1400
December	1st to 10th	Day	18% 17% 5% 12% 7% 7% 6% 3 5% 4 15%	1365
	11th to 20th	Day	20% 16% 5% 8% 6% 4 4 3 4 6% 22%	1668
	21st to end	Day	16% 16% 6% 12% 8% 6% 5% 4 5% 5% 16%	2431
January	1st to 10th	Night	14% 19% 7% 14% 8% 6% 5% 3 4 5% 15%	4494
	11th to 20th	Night	13% 15% 5% 16% 8% 7% 6% 4 5% 5% 16%	4440
	21st to end	Night	7% 14% 6% 14% 9% 7% 5% 4 6% 6% 22%	4884
February	1st to 10th	Night	9% 12% 5% 13% 8% 7% 6% 4 5% 6% 25%	2660
	11th to 20th	Night	10% 17% 5% 13% 9% 6% 6% 4 6% 5% 19%	2328
	21st to end	Night	11% 16% 4 10% 7% 6% 4 3 5% 6% 26%	1884
March	1st to 10th	Night	16% 13% 4 9% 6% 5% 7% 5% 6% 6% 23%	3724
	11th to 20th	Night	15% 15% 6% 13% 6% 6% 5% 4 5% 5% 20%	3707
	21st to end	Night	12% 15% 4 10% 6% 5% 5% 4 5% 7% 26%	3476
April	1st to 10th	Night	21% 16% 4 8% 4 4 4 3 4 5% 26%	1900
	11th to 20th	Night	19% 11% 3 6% 5% 5% 5% 4 5% 6% 32%	1787
	21st to end	Night	18% 10% 3 8% 6% 4 3 4 5% 6% 33%	1710
May	1st to 10th	Night	18% 10% 3 8% 5% 4 5% 3 5% 6% 33%	2546
	11th to 20th	Night	20% 9% 3 7% 4 5% 4 4 6% 6% 33%	2495
	21st to end	Night	20% 8% 2 8% 5% 4 5% 4 5% 8% 31%	2528
June	1st to 10th	Night	19% 8% 3 8% 6% 6% 5% 5% 7% 7% 28%	1330
	11th to 20th	Night	16% 8% 3 7% 5% 4 5% 3 6% 7% 37%	1330
	21st to end	Night	17% 7% 3 8% 5% 5% 6% 5% 8% 8% 29%	1330
July	1st to 10th	Night	15% 6% 2 9% 7% 6% 7% 5% 7% 7% 29%	2258
	11th to 20th	Night	11% 6% 3 8% 6% 6% 5% 5% 8% 9% 33%	2520
	21st to end	Night	12% 6% 2 7% 5% 5% 5% 4 6% 8% 40%	2739
August	1st to 10th	Night	14% 6% 3 8% 5% 6% 6% 4 8% 9% 31%	2506
	11th to 20th	Night	15% 7% 3 8% 5% 4 4 4 6% 9% 35%	2616
	21st to end	Night	14% 7% 2 7% 4 4 5% 4 6% 8% 38%	3316
September	1st to 10th	Night	16% 7% 3 7% 5% 3 5% 3 5% 7% 38%	1900
	11th to 20th	Night	20% 7% 3 7% 4 4 4 4 4 6% 36%	2023
	21st to end	Night	20% 7% 3 8% 4 5% 5% 4 5% 5% 35%	2090
October	1st to 10th	Night	20% 8% 2 6% 5% 4 4 4 5% 7% 35%	2166
	11th to 20th	Night	28% 12% 4 7% 4 5% 4 3 5% 6% 22%	2427
	21st to end	Night	28% 12% 3 8% 5% 5% 5% 4 5% 5% 20%	2717
November	1st to 10th	Night	23% 14% 4 8% 5% 4 4 4 4 6% 22%	2537
	11th to 20th	Night	20% 16% 5% 11% 5% 5% 4 3 5% 6% 20%	2771
	21st to end	Night	23% 18% 5% 12% 6% 5% 5% 3 4 4 15%	3000
December	1st to 10th	Night	18% 19% 6% 13% 8% 5% 4 3 4 4 17%	2932
	11th to 20th	Night	22% 15% 5% 10% 5% 4 4 4 5% 5% 20%	3531
	21st to end	Night	15% 21% 8% 12% 5% 4 4 3 3 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	74% 2 10% 11% 3	2439
	11th to 20th	Day	72% 2 8% 14% 4	2520
	21st to end	Day	58% 2 11% 21% 8%	2772
February	1st to 10th	Day	60% 3 8% 19% 9% 1	1520
	11th to 20th	Day	64% 3 8% 16% 8%	1743
	21st to end	Day	58% 4 8% 20% 9% 1	1570
March	1st to 10th	Day	54% 3 11% 18% 12% 1	3119
	11th to 20th	Day	65% 2 9% 17% 6%	3251
	21st to end	Day	55% 2 9% 18% 15% 2	4152
April	1st to 10th	Day	62% 2 9% 15% 9% 3	2280
	11th to 20th	Day	51% 2 9% 25% 12% 1	2342
	21st to end	Day	55% 2 8% 21% 13% 1	2470
May	1st to 10th	Day	54% 1 11% 20% 13% 1	4438
	11th to 20th	Day	50% 2 9% 25% 12% 1	4402
	21st to end	Day	50% 2 7% 23% 17% 2	5054
June	1st to 10th	Day	53% 3 8% 22% 13% 1	2850
	11th to 20th	Day	47% 4 12% 22% 12% 2	2850
	21st to end	Day	54% 3 11% 21% 10% 1	2850
July	1st to 10th	Day	50% 5% 14% 27% 4	4632
	11th to 20th	Day	48% 6% 17% 24% 5%	4365
	21st to end	Day	46% 4 18% 25% 7%	4661
August	1st to 10th	Day	51% 5% 18% 23% 2	4409
	11th to 20th	Day	51% 5% 20% 20% 4	4222
	21st to end	Day	49% 5% 14% 20% 12%	4323
September	1st to 10th	Day	51% 3 15% 22% 8%	2280
	11th to 20th	Day	48% 4 19% 23% 6%	2157
	21st to end	Day	55% 4 13% 22% 6%	2090
October	1st to 10th	Day	55% 4 13% 23% 4 1	3335
	11th to 20th	Day	67% 4 14% 14% 2	2890
	21st to end	Day	63% 4 15% 14% 3	3081
November	1st to 10th	Day	66% 2 11% 15% 5% 1	1761
	11th to 20th	Day	67% 3 11% 16% 4	1625
	21st to end	Day	72% 3 10% 12% 3	1400
December	1st to 10th	Day	71% 3 8% 14% 3	1365
	11th to 20th	Day	65% 3 6% 21% 6%	1668
	21st to end	Day	71% 1 8% 11% 8%	2431
January	1st to 10th	Night	73% 1 8% 12% 4	4494
	11th to 20th	Night	72% 2 7% 15% 4	4440
	21st to end	Night	64% 2 8% 19% 6%	4884
February	1st to 10th	Night	59% 3 9% 19% 10%	2660
	11th to 20th	Night	67% 2 8% 16% 7%	2330
	21st to end	Night	59% 3 9% 21% 9%	1884
March	1st to 10th	Night	62% 2 10% 18% 7% 1	3734
	11th to 20th	Night	67% 1 8% 16% 7% 1	3708
	21st to end	Night	58% 2 7% 22% 10% 1	3476
April	1st to 10th	Night	62% 3 7% 18% 8% 3	1900
	11th to 20th	Night	53% 2 7% 25% 12%	1787
	21st to end	Night	52% 3 8% 22% 14% 2	1710
May	1st to 10th	Night	54% 2 8% 21% 14% 2	2552
	11th to 20th	Night	54% 1 7% 25% 12% 2	2496
	21st to end	Night	54% 2 7% 21% 16% 1	2529
June	1st to 10th	Night	54% 4 9% 23% 10% 1	1330
	11th to 20th	Night	47% 4 9% 22% 14% 4	1330
	21st to end	Night	52% 4 12% 21% 11%	1330
July	1st to 10th	Night	52% 5% 12% 25% 6%	2222
	11th to 20th	Night	45% 6% 17% 25% 6%	2472
	21st to end	Night	42% 5% 18% 24% 11%	2651
August	1st to 10th	Night	48% 6% 19% 22% 5%	2496
	11th to 20th	Night	46% 5% 25% 19% 5%	2640
	21st to end	Night	44% 4 15% 29% 8%	3316
September	1st to 10th	Night	45% 4 15% 26% 9% 1	1900
	11th to 20th	Night	50% 2 18% 24% 6%	2023
	21st to end	Night	52% 3 13% 25% 7%	2090
October	1st to 10th	Night	52% 4 14% 23% 6% 1	3608
	11th to 20th	Night	62% 3 13% 19% 4	4028
	21st to end	Night	65% 4 13% 13% 5%	4467
November	1st to 10th	Night	65% 3 13% 15% 5%	2537
	11th to 20th	Night	66% 3 11% 15% 4	2771
	21st to end	Night	74% 2 9% 12% 3	3000
December	1st to 10th	Night	73% 2 9% 14% 2	2932
	11th to 20th	Night	66% 2 8% 18% 6%	3532
	21st to end	Night	71% 1 9% 11% 7% 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% 7% 29% 32% 9% 1	180
	11th to 20th	Day	18% 7% 29% 28% 17% 2	180
	21st to end	Day	17% 6% 25% 31% 16% 6%	198
February	1st to 10th	Day	15% 10% 36% 25% 11% 3	180
	11th to 20th	Day	20% 11% 32% 26% 10%	353
	21st to end	Day	22% 10% 35% 22% 10% 1	382
March	1st to 10th	Day	22% 10% 29% 25% 13% 1	460
	11th to 20th	Day	25% 7% 29% 25% 11% 3	460
	21st to end	Day	25% 10% 28% 25% 9% 3	506
April	1st to 10th	Day	25% 11% 23% 29% 10% 2	460
	11th to 20th	Day	21% 10% 27% 27% 13% 2	452
	21st to end	Day	25% 9% 33% 20% 12% 2	460
May	1st to 10th	Day	28% 11% 25% 22% 11% 3	463
	11th to 20th	Day	20% 9% 28% 26% 14% 4	487
	21st to end	Day	23% 10% 31% 26% 9% 1	655
June	1st to 10th	Day	26% 6% 27% 26% 13% 2	680
	11th to 20th	Day	20% 5% 27% 31% 14% 4	680
	21st to end	Day	24% 5% 23% 28% 16% 4	680
July	1st to 10th	Day	19% 6% 24% 33% 15% 3	643
	11th to 20th	Day	20% 5% 24% 30% 16% 6%	484
	21st to end	Day	19% 3 23% 26% 23% 6%	532
August	1st to 10th	Day	18% 4 23% 29% 17% 8%	486
	11th to 20th	Day	19% 4 16% 31% 20% 9%	479
	21st to end	Day	23% 6% 24% 22% 16% 9%	539
September	1st to 10th	Day	22% 6% 27% 22% 16% 7%	490
	11th to 20th	Day	20% 7% 24% 27% 16% 6%	490
	21st to end	Day	24% 7% 23% 23% 17% 6%	490
October	1st to 10th	Day	24% 9% 26% 22% 14% 5%	490
	11th to 20th	Day	33% 8% 26% 20% 11% 3	412
	21st to end	Day	35% 8% 26% 21% 9% 1	429
November	1st to 10th	Day	32% 13% 28% 21% 4 1	395
	11th to 20th	Day	30% 11% 27% 20% 10% 2	260
	21st to end	Day	31% 9% 30% 21% 6% 4	200
December	1st to 10th	Day	21% 9% 21% 27% 17% 5%	190
	11th to 20th	Day	23% 8% 36% 23% 6% 4	180
	21st to end	Day	29% 9% 25% 22% 12% 3	198
January	1st to 10th	Night	23% 6% 29% 33% 8%	778
	11th to 20th	Night	23% 8% 28% 29% 11% 1	760
	21st to end	Night	15% 5% 24% 40% 14% 1	836
February	1st to 10th	Night	14% 6% 30% 35% 13% 2	760
	11th to 20th	Night	20% 6% 31% 32% 9% 1	743
	21st to end	Night	18% 9% 29% 31% 11% 2	628
March	1st to 10th	Night	21% 7% 31% 33% 8%	760
	11th to 20th	Night	23% 9% 28% 27% 12%	760
	21st to end	Night	22% 8% 30% 30% 9% 1	836
April	1st to 10th	Night	30% 7% 24% 30% 8% 1	760
	11th to 20th	Night	25% 7% 30% 30% 8%	663
	21st to end	Night	22% 11% 33% 25% 8%	570
May	1st to 10th	Night	25% 8% 31% 27% 8% 1	399
	11th to 20th	Night	25% 7% 30% 29% 8% 1	374
	21st to end	Night	26% 6% 32% 29% 7% 1	411
June	1st to 10th	Night	23% 4 27% 36% 7% 1	380
	11th to 20th	Night	20% 2 26% 37% 14% 1	380
	21st to end	Night	22% 5% 22% 36% 14% 1	380
July	1st to 10th	Night	21% 2 25% 39% 13% 1	370
	11th to 20th	Night	17% 1 22% 41% 19%	368
	21st to end	Night	21% 2 17% 41% 18% 1	416
August	1st to 10th	Night	18% 3 17% 44% 17% 1	378
	11th to 20th	Night	21% 2 18% 35% 23% 2	457
	21st to end	Night	20% 4 21% 33% 19% 3	741
September	1st to 10th	Night	21% 4 22% 37% 15% 1	760
	11th to 20th	Night	25% 5% 21% 32% 15% 2	760
	21st to end	Night	24% 4 27% 31% 12% 2	760
October	1st to 10th	Night	24% 5% 26% 31% 12% 1	760
	11th to 20th	Night	35% 5% 24% 26% 9% 1	760
	21st to end	Night	36% 6% 26% 24% 8%	836
November	1st to 10th	Night	33% 9% 24% 26% 7% 2	780
	11th to 20th	Night	29% 8% 28% 26% 9%	817
	21st to end	Night	32% 9% 28% 24% 7% 1	900
December	1st to 10th	Night	28% 7% 25% 29% 10% 1	878
	11th to 20th	Night	25% 9% 26% 28% 11% 1	850
	21st to end	Night	28% 8% 25% 27% 10% 2	935

Page generated at 2024-12-03 06:45:09. Version ac07

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