Val-d'Or
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Val-d'Or clear sky chart from 2005-11-06 to 2025-12-03.

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% 13% 4 10% 6% 5% 5% 4 5% 6% 26%	127483
	Night	16% 15% 6% 12% 6% 5% 5% 3 4 5% 23%	123271
Transparency	Day	58% 6% 11% 17% 7% 1	130963
	Night	63% 5% 10% 15% 7% 1	127879
Seeing	Day	24% 16% 32% 19% 7% 2	16379
	Night	25% 13% 30% 23% 8% 1	25199

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	12% 22% 10% 19% 7% 7% 6% 3 4 3 6%	3158
	11th to 20th	Day	9% 17% 7% 20% 9% 5% 6% 6% 6% 4 11%	3332
	21st to end	Day	9% 17% 8% 15% 8% 5% 5% 4 4 5% 19%	4124
February	1st to 10th	Day	9% 15% 7% 15% 10% 9% 5% 3 5% 5% 16%	1800
	11th to 20th	Day	10% 21% 7% 14% 8% 5% 7% 4 4 4 17%	1753
	21st to end	Day	12% 17% 6% 14% 7% 5% 4 4 5% 5% 21%	1522
March	1st to 10th	Day	19% 16% 4 12% 6% 4 4 3 4 4 22%	4677
	11th to 20th	Day	17% 15% 6% 14% 7% 4 3 3 4 4 23%	4980
	21st to end	Day	13% 16% 6% 12% 7% 6% 4 2 3 3 26%	5616
April	1st to 10th	Day	20% 17% 5% 8% 6% 5% 3 3 4 5% 24%	2400
	11th to 20th	Day	21% 13% 4 8% 5% 4 3 3 4 5% 30%	2453
	21st to end	Day	21% 13% 3 8% 4 4 4 3 5% 5% 30%	2635
May	1st to 10th	Day	17% 13% 4 7% 5% 4 4 3 5% 5% 33%	6346
	11th to 20th	Day	15% 9% 3 8% 5% 5% 5% 4 6% 7% 33%	6318
	21st to end	Day	20% 12% 3 7% 4 4 4 3 4 6% 34%	6949
June	1st to 10th	Day	22% 9% 3 7% 4 4 5% 5% 6% 8% 29%	2941
	11th to 20th	Day	16% 9% 2 8% 6% 5% 5% 4 6% 7% 33%	3000
	21st to end	Day	20% 8% 3 7% 5% 4 6% 4 6% 7% 30%	3000
July	1st to 10th	Day	16% 7% 3 7% 6% 5% 6% 5% 8% 10% 27%	6819
	11th to 20th	Day	18% 7% 2 7% 5% 5% 5% 5% 6% 8% 33%	6732
	21st to end	Day	16% 8% 3 7% 5% 5% 5% 5% 6% 8% 33%	6926
August	1st to 10th	Day	17% 7% 3 7% 6% 5% 5% 4 6% 8% 32%	4474
	11th to 20th	Day	19% 8% 3 6% 4 5% 5% 4 6% 8% 32%	4174
	21st to end	Day	15% 8% 3 7% 4 5% 4 4 6% 7% 36%	4488
September	1st to 10th	Day	21% 8% 3 7% 5% 4 4 4 7% 7% 32%	2400
	11th to 20th	Day	20% 7% 3 7% 4 4 4 3 6% 8% 34%	2400
	21st to end	Day	23% 10% 3 6% 5% 3 3 4 4 6% 32%	2090
October	1st to 10th	Day	22% 13% 3 7% 4 4 3 3 5% 5% 31%	2000
	11th to 20th	Day	28% 20% 5% 7% 4 3 4 3 3 5% 17%	2000
	21st to end	Day	28% 20% 5% 8% 5% 4 3 3 4 5% 15%	2070
November	1st to 10th	Day	20% 23% 5% 10% 5% 4 4 2 4 4 18%	1654
	11th to 20th	Day	21% 22% 6% 15% 7% 4 4 3 3 4 12%	1680
	21st to end	Day	25% 25% 7% 15% 7% 5% 3 2 3 3 6%	1680
December	1st to 10th	Day	13% 27% 11% 18% 8% 5% 4 2 3 3 7%	2616
	11th to 20th	Day	14% 22% 6% 15% 11% 7% 4 3 3 3 13%	2800
	21st to end	Day	18% 20% 8% 16% 9% 5% 5% 3 3 3 11%	3476
January	1st to 10th	Night	12% 21% 11% 21% 9% 5% 4 2 2 3 10%	6808
	11th to 20th	Night	9% 18% 8% 21% 9% 7% 7% 4 4 4 11%	6547
	21st to end	Night	7% 17% 10% 16% 7% 7% 8% 4 5% 4 15%	6830
February	1st to 10th	Night	10% 17% 6% 12% 9% 7% 7% 5% 5% 6% 17%	2600
	11th to 20th	Night	12% 18% 6% 14% 9% 6% 5% 4 5% 5% 17%	2533
	21st to end	Night	10% 15% 7% 13% 9% 7% 7% 4 4 5% 18%	2106
March	1st to 10th	Night	15% 19% 6% 11% 6% 4 4 4 4 4 23%	5162
	11th to 20th	Night	16% 19% 6% 13% 6% 6% 5% 3 4 4 17%	4979
	21st to end	Night	14% 13% 5% 12% 7% 7% 5% 3 4 4 26%	5315
April	1st to 10th	Night	19% 16% 5% 10% 5% 3 3 3 4 5% 27%	2000
	11th to 20th	Night	17% 11% 4 10% 4 5% 4 3 5% 6% 31%	1912
	21st to end	Night	20% 10% 4 8% 4 4 3 3 5% 6% 32%	1765
May	1st to 10th	Night	17% 11% 3 7% 5% 4 4 3 5% 5% 35%	3594
	11th to 20th	Night	16% 10% 3 7% 4 3 4 3 5% 6% 39%	3575
	21st to end	Night	20% 8% 3 6% 4 4 5% 4 5% 8% 33%	3926
June	1st to 10th	Night	20% 8% 2 9% 5% 5% 5% 4 6% 7% 30%	1455
	11th to 20th	Night	18% 9% 3 7% 4 4 4 4 5% 7% 36%	1400
	21st to end	Night	17% 7% 2 7% 5% 5% 5% 5% 5% 7% 35%	1400
July	1st to 10th	Night	18% 8% 3 8% 5% 4 4 4 5% 7% 33%	3160
	11th to 20th	Night	17% 8% 3 7% 5% 4 5% 4 6% 7% 35%	3243
	21st to end	Night	15% 7% 2 7% 4 3 4 3 5% 7% 42%	3926
August	1st to 10th	Night	13% 6% 2 7% 5% 5% 6% 5% 7% 9% 35%	2673
	11th to 20th	Night	16% 9% 3 8% 4 3 4 3 6% 7% 36%	2875
	21st to end	Night	16% 7% 3 7% 5% 5% 5% 4 5% 8% 36%	3376
September	1st to 10th	Night	18% 8% 3 6% 4 4 4 3 6% 6% 37%	2000
	11th to 20th	Night	19% 8% 3 6% 4 3 4 3 5% 7% 39%	2000
	21st to end	Night	22% 8% 3 7% 5% 3 3 2 4 5% 38%	2306
October	1st to 10th	Night	21% 10% 3 7% 5% 4 3 3 5% 6% 33%	2400
	11th to 20th	Night	27% 16% 4 8% 4 4 4 3 4 5% 20%	2400
	21st to end	Night	27% 21% 4 8% 3 3 3 3 4 4 20%	2768
November	1st to 10th	Night	20% 19% 6% 10% 5% 4 3 3 4 5% 20%	2862
	11th to 20th	Night	20% 21% 7% 12% 6% 4 4 2 4 4 15%	2940
	21st to end	Night	24% 24% 6% 14% 7% 4 3 2 3 3 9%	2940
December	1st to 10th	Night	14% 25% 9% 18% 10% 7% 3 2 2 2 7%	4609
	11th to 20th	Night	18% 21% 6% 14% 8% 7% 6% 3 3 3 11%	5384
	21st to end	Night	19% 20% 8% 17% 8% 4 5% 3 2 3 12%	7502

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	84% 4 7% 4 1	3159
	11th to 20th	Day	74% 5% 6% 9% 6%	3361
	21st to end	Day	68% 3 6% 16% 6%	4124
February	1st to 10th	Day	70% 4 7% 11% 7%	1800
	11th to 20th	Day	70% 4 7% 12% 6%	1762
	21st to end	Day	65% 5% 7% 16% 6% 1	1522
March	1st to 10th	Day	66% 4 6% 14% 9% 1	4680
	11th to 20th	Day	65% 4 8% 15% 7% 1	4980
	21st to end	Day	62% 5% 6% 19% 8% 1	5616
April	1st to 10th	Day	62% 5% 9% 13% 10% 1	2400
	11th to 20th	Day	56% 4 9% 18% 11% 2	2453
	21st to end	Day	56% 5% 8% 16% 14% 2	2635
May	1st to 10th	Day	50% 7% 9% 16% 15% 4	6357
	11th to 20th	Day	46% 9% 15% 20% 9% 1	6322
	21st to end	Day	51% 6% 9% 18% 14% 2	6949
June	1st to 10th	Day	51% 8% 11% 19% 10% 1	2941
	11th to 20th	Day	48% 7% 10% 22% 12% 2	3000
	21st to end	Day	51% 8% 12% 20% 8% 1	3000
July	1st to 10th	Day	49% 7% 16% 24% 4	6746
	11th to 20th	Day	46% 7% 18% 23% 7%	6651
	21st to end	Day	47% 7% 14% 25% 7%	6728
August	1st to 10th	Day	47% 7% 16% 24% 5%	4460
	11th to 20th	Day	47% 8% 16% 22% 8%	4213
	21st to end	Day	45% 7% 13% 26% 10%	4488
September	1st to 10th	Day	49% 9% 14% 19% 8% 1	2400
	11th to 20th	Day	48% 8% 17% 22% 5%	2400
	21st to end	Day	54% 7% 12% 20% 7%	2090
October	1st to 10th	Day	57% 6% 10% 21% 5%	3260
	11th to 20th	Day	64% 5% 12% 14% 5%	3240
	21st to end	Day	70% 5% 13% 7% 4	3321
November	1st to 10th	Day	69% 6% 12% 9% 3	1654
	11th to 20th	Day	78% 5% 7% 8% 3	1680
	21st to end	Day	86% 3 5% 4 1	1680
December	1st to 10th	Day	85% 3 5% 6% 1	2616
	11th to 20th	Day	77% 5% 5% 11% 2	2799
	21st to end	Day	80% 3 5% 10% 2	3476
January	1st to 10th	Night	81% 4 7% 5% 3	6808
	11th to 20th	Night	77% 5% 6% 7% 5%	6593
	21st to end	Night	71% 5% 5% 13% 5%	6830
February	1st to 10th	Night	66% 6% 8% 12% 8%	2600
	11th to 20th	Night	69% 5% 7% 13% 6%	2535
	21st to end	Night	67% 5% 8% 13% 7%	2106
March	1st to 10th	Night	64% 4 7% 11% 11% 3	5172
	11th to 20th	Night	70% 5% 8% 10% 6% 1	4980
	21st to end	Night	59% 5% 7% 17% 9% 2	5315
April	1st to 10th	Night	61% 4 7% 15% 12% 1	2000
	11th to 20th	Night	52% 6% 9% 20% 12% 1	1912
	21st to end	Night	53% 5% 8% 16% 15% 2	1765
May	1st to 10th	Night	49% 7% 10% 16% 15% 3	3600
	11th to 20th	Night	44% 8% 12% 21% 12% 3	3576
	21st to end	Night	47% 7% 12% 17% 15% 1	3927
June	1st to 10th	Night	51% 8% 11% 18% 10% 1	1455
	11th to 20th	Night	46% 7% 10% 20% 14% 3	1400
	21st to end	Night	46% 8% 13% 21% 11% 1	1400
July	1st to 10th	Night	49% 6% 12% 25% 7%	3125
	11th to 20th	Night	47% 6% 15% 24% 7%	3201
	21st to end	Night	41% 6% 18% 28% 7%	3809
August	1st to 10th	Night	43% 8% 18% 26% 5%	2663
	11th to 20th	Night	46% 7% 16% 24% 6%	2902
	21st to end	Night	45% 7% 15% 23% 7% 2	3376
September	1st to 10th	Night	46% 9% 16% 20% 9% 1	2000
	11th to 20th	Night	45% 8% 17% 23% 6%	2000
	21st to end	Night	49% 6% 14% 24% 7%	2306
October	1st to 10th	Night	53% 5% 12% 21% 8% 1	3920
	11th to 20th	Night	62% 5% 11% 19% 3	3899
	21st to end	Night	63% 5% 14% 10% 7% 1	4467
November	1st to 10th	Night	67% 6% 12% 12% 2	2862
	11th to 20th	Night	73% 6% 8% 9% 3	2940
	21st to end	Night	82% 4 7% 5% 1	2940
December	1st to 10th	Night	85% 4 5% 5% 1	4609
	11th to 20th	Night	79% 3 6% 10% 2	5384
	21st to end	Night	80% 3 4 10% 3	7502

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	21% 21% 43% 11% 4 2	200
	11th to 20th	Day	19% 16% 37% 20% 7% 3	200
	21st to end	Day	17% 15% 38% 21% 8% 1	257
February	1st to 10th	Day	22% 24% 39% 11% 3 1	300
	11th to 20th	Day	22% 24% 39% 12% 2	300
	21st to end	Day	26% 20% 39% 14% 2	286
March	1st to 10th	Day	23% 19% 38% 15% 4 1	500
	11th to 20th	Day	26% 18% 35% 16% 5%	500
	21st to end	Day	24% 21% 34% 15% 4 1	550
April	1st to 10th	Day	29% 20% 27% 15% 7% 2	500
	11th to 20th	Day	29% 17% 28% 17% 6% 3	492
	21st to end	Day	29% 17% 32% 16% 4 1	500
May	1st to 10th	Day	23% 17% 35% 18% 7% 1	503
	11th to 20th	Day	24% 17% 33% 18% 6% 2	527
	21st to end	Day	25% 17% 30% 21% 6% 1	573
June	1st to 10th	Day	25% 15% 34% 20% 6% 1	671
	11th to 20th	Day	22% 16% 34% 20% 7% 2	730
	21st to end	Day	20% 13% 32% 26% 8% 1	730
July	1st to 10th	Day	17% 14% 34% 25% 9% 2	721
	11th to 20th	Day	18% 13% 33% 25% 10% 1	682
	21st to end	Day	19% 9% 31% 27% 11% 2	576
August	1st to 10th	Day	18% 9% 33% 25% 12% 4	526
	11th to 20th	Day	19% 8% 26% 27% 13% 6%	519
	21st to end	Day	21% 12% 30% 20% 11% 5%	583
September	1st to 10th	Day	23% 12% 34% 19% 10% 2	530
	11th to 20th	Day	19% 11% 28% 26% 12% 4	530
	21st to end	Day	25% 14% 30% 17% 12% 2	530
October	1st to 10th	Day	29% 14% 27% 20% 8% 2	530
	11th to 20th	Day	34% 21% 26% 13% 5% 1	530
	21st to end	Day	36% 14% 29% 16% 5% 1	511
November	1st to 10th	Day	36% 22% 33% 7% 2	228
	11th to 20th	Day	30% 20% 34% 15% 1	220
	21st to end	Day	36% 22% 30% 7% 3 1	220
December	1st to 10th	Day	26% 16% 30% 20% 7% 1	204
	11th to 20th	Day	27% 17% 42% 10% 4 2	200
	21st to end	Day	29% 16% 34% 14% 5% 2	220
January	1st to 10th	Night	28% 13% 36% 19% 5%	1000
	11th to 20th	Night	25% 14% 34% 22% 6%	903
	21st to end	Night	16% 12% 32% 28% 12% 1	880
February	1st to 10th	Night	16% 20% 35% 23% 6%	800
	11th to 20th	Night	21% 15% 36% 23% 4	783
	21st to end	Night	18% 20% 34% 22% 5%	660
March	1st to 10th	Night	22% 20% 29% 23% 6%	800
	11th to 20th	Night	26% 19% 30% 20% 4 1	800
	21st to end	Night	22% 15% 34% 22% 6% 1	880
April	1st to 10th	Night	29% 14% 28% 23% 6% 1	800
	11th to 20th	Night	24% 17% 28% 21% 9% 1	728
	21st to end	Night	26% 11% 32% 24% 6% 1	565
May	1st to 10th	Night	22% 9% 35% 25% 10% 1	400
	11th to 20th	Night	23% 9% 31% 28% 8% 1	394
	21st to end	Night	25% 9% 31% 29% 6%	433
June	1st to 10th	Night	21% 10% 36% 26% 7%	400
	11th to 20th	Night	22% 9% 31% 31% 7%	400
	21st to end	Night	20% 6% 27% 35% 13%	400
July	1st to 10th	Night	17% 8% 29% 34% 10% 1	390
	11th to 20th	Night	15% 5% 32% 35% 13%	388
	21st to end	Night	15% 8% 24% 39% 13% 1	438
August	1st to 10th	Night	17% 4 28% 32% 16% 2	446
	11th to 20th	Night	16% 6% 28% 27% 21% 2	594
	21st to end	Night	20% 9% 26% 28% 14% 3	748
September	1st to 10th	Night	22% 10% 31% 23% 13% 1	800
	11th to 20th	Night	23% 8% 27% 27% 14% 1	800
	21st to end	Night	26% 10% 26% 26% 12% 1	800
October	1st to 10th	Night	26% 12% 28% 24% 9% 1	800
	11th to 20th	Night	36% 13% 28% 16% 6% 1	800
	21st to end	Night	38% 12% 28% 18% 5%	880
November	1st to 10th	Night	32% 15% 31% 15% 6% 1	820
	11th to 20th	Night	32% 16% 29% 17% 6%	840
	21st to end	Night	35% 17% 31% 14% 3	840
December	1st to 10th	Night	32% 16% 29% 16% 6% 1	809
	11th to 20th	Night	27% 16% 31% 19% 5% 2	880
	21st to end	Night	30% 17% 26% 20% 6% 1	1100

Page generated at 2025-11-30 01:00:52. Version ac07

Copyright © 2025 Attilla Danko.