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 2024-11-10.

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% 13% 4 9% 6% 5% 5% 4 5% 6% 26%	101848
	Night	17% 14% 5% 11% 6% 5% 5% 3 4 5% 24%	97328
Transparency	Day	57% 7% 11% 17% 7% 1	105346
	Night	61% 6% 11% 15% 7% 1	101919
Seeing	Day	24% 16% 32% 19% 7% 2	15041
	Night	25% 13% 30% 23% 8% 1	23851

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	15% 23% 9% 13% 4 8% 7% 3 5% 4 8%	2208
	11th to 20th	Day	10% 15% 8% 21% 8% 5% 8% 6% 4 4 12%	2346
	21st to end	Day	12% 21% 10% 15% 7% 5% 4 3 4 4 15%	2880
February	1st to 10th	Day	10% 15% 6% 15% 10% 9% 6% 3 5% 5% 16%	1710
	11th to 20th	Day	10% 21% 6% 14% 8% 5% 7% 4 4 5% 17%	1663
	21st to end	Day	12% 17% 6% 13% 7% 5% 4 4 5% 5% 21%	1448
March	1st to 10th	Day	19% 16% 4 10% 5% 4 4 3 4 5% 26%	3261
	11th to 20th	Day	11% 18% 7% 17% 6% 4 4 3 4 4 25%	3480
	21st to end	Day	11% 14% 5% 13% 7% 7% 5% 3 4 4 27%	3924
April	1st to 10th	Day	21% 18% 5% 7% 6% 4 3 3 4 5% 25%	2280
	11th to 20th	Day	21% 12% 4 9% 5% 4 4 3 4 5% 29%	2329
	21st to end	Day	21% 13% 3 8% 4 4 4 3 5% 5% 31%	2503
May	1st to 10th	Day	18% 12% 4 8% 5% 5% 5% 3 5% 6% 28%	4426
	11th to 20th	Day	17% 10% 3 7% 5% 5% 5% 5% 6% 7% 30%	4398
	21st to end	Day	19% 9% 3 6% 5% 4 4 3 5% 7% 35%	4837
June	1st to 10th	Day	22% 9% 3 7% 4 4 5% 5% 6% 8% 28%	2794
	11th to 20th	Day	16% 9% 2 7% 6% 5% 5% 4 6% 7% 33%	2850
	21st to end	Day	19% 8% 3 7% 6% 4 6% 4 6% 7% 30%	2850
July	1st to 10th	Day	17% 7% 3 7% 5% 5% 5% 5% 7% 9% 29%	4760
	11th to 20th	Day	18% 7% 2 7% 5% 5% 5% 5% 6% 8% 33%	4700
	21st to end	Day	16% 7% 2 7% 5% 5% 5% 4 6% 8% 35%	4814
August	1st to 10th	Day	17% 7% 3 7% 6% 5% 5% 4 6% 8% 31%	4337
	11th to 20th	Day	20% 8% 3 6% 4 5% 5% 4 6% 8% 32%	4044
	21st to end	Day	15% 7% 3 7% 4 5% 4 4 5% 7% 37%	4351
September	1st to 10th	Day	21% 8% 3 7% 4 4 4 4 6% 7% 33%	2280
	11th to 20th	Day	21% 8% 3 7% 4 4 4 3 6% 8% 33%	2280
	21st to end	Day	24% 11% 4 7% 5% 3 3 4 4 6% 30%	1986
October	1st to 10th	Day	22% 13% 3 8% 4 4 3 3 5% 5% 30%	1900
	11th to 20th	Day	29% 21% 5% 7% 4 3 4 3 3 5% 16%	1900
	21st to end	Day	29% 19% 5% 8% 5% 4 3 3 4 5% 15%	1967
November	1st to 10th	Day	21% 22% 5% 10% 5% 4 4 2 3 4 19%	1566
	11th to 20th	Day	22% 21% 6% 14% 7% 5% 3 3 3 4 12%	1520
	21st to end	Day	25% 22% 7% 14% 8% 5% 3 2 3 3 7%	1520
December	1st to 10th	Day	18% 24% 8% 14% 7% 6% 5% 2 3 3 11%	1520
	11th to 20th	Day	17% 20% 6% 13% 10% 5% 5% 4 4 3 12%	1785
	21st to end	Day	18% 20% 9% 17% 8% 4 4 2 3 3 11%	2431
January	1st to 10th	Night	14% 19% 8% 17% 8% 7% 6% 3 3 3 11%	4748
	11th to 20th	Night	10% 16% 7% 18% 9% 7% 7% 4 4 4 13%	4603
	21st to end	Night	9% 19% 11% 15% 8% 8% 6% 4 5% 4 11%	4774
February	1st to 10th	Night	10% 17% 5% 12% 8% 7% 7% 5% 5% 6% 18%	2470
	11th to 20th	Night	12% 18% 6% 13% 8% 6% 5% 4 5% 5% 17%	2403
	21st to end	Night	11% 15% 6% 13% 9% 6% 7% 4 4 5% 18%	2004
March	1st to 10th	Night	14% 17% 4 9% 6% 4 5% 3 5% 5% 27%	3578
	11th to 20th	Night	15% 21% 7% 13% 6% 5% 5% 3 3 5% 19%	3479
	21st to end	Night	13% 11% 5% 13% 6% 6% 5% 3 5% 5% 29%	3707
April	1st to 10th	Night	20% 16% 5% 10% 5% 3 3 3 4 4 27%	1900
	11th to 20th	Night	17% 12% 4 9% 5% 4 4 3 5% 6% 31%	1815
	21st to end	Night	19% 10% 4 8% 5% 4 3 3 5% 6% 33%	1677
May	1st to 10th	Night	19% 10% 3 8% 6% 5% 5% 3 5% 6% 30%	2514
	11th to 20th	Night	16% 10% 3 8% 5% 4 4 3 5% 7% 35%	2495
	21st to end	Night	21% 7% 3 6% 4 4 5% 5% 6% 9% 31%	2738
June	1st to 10th	Night	21% 8% 3 9% 6% 5% 5% 4 5% 7% 29%	1382
	11th to 20th	Night	18% 8% 3 7% 4 4 4 4 5% 7% 36%	1330
	21st to end	Night	16% 7% 2 6% 5% 5% 5% 5% 5% 7% 36%	1330
July	1st to 10th	Night	18% 8% 3 7% 5% 4 4 4 5% 7% 35%	2210
	11th to 20th	Night	17% 9% 3 7% 5% 5% 5% 4 6% 7% 34%	2267
	21st to end	Night	17% 8% 2 7% 4 3 4 3 5% 7% 40%	2739
August	1st to 10th	Night	13% 6% 3 8% 5% 5% 6% 5% 7% 9% 34%	2590
	11th to 20th	Night	17% 9% 3 8% 4 3 4 3 6% 7% 36%	2785
	21st to end	Night	15% 7% 3 7% 5% 5% 5% 4 5% 8% 36%	3272
September	1st to 10th	Night	19% 8% 3 6% 4 4 4 4 5% 6% 37%	1900
	11th to 20th	Night	20% 8% 3 6% 4 3 4 3 5% 6% 38%	1900
	21st to end	Night	23% 8% 3 7% 5% 3 3 2 4 5% 37%	2190
October	1st to 10th	Night	22% 10% 4 7% 5% 4 4 2 5% 6% 33%	2280
	11th to 20th	Night	27% 17% 4 8% 4 4 4 3 4 5% 20%	2280
	21st to end	Night	27% 21% 4 8% 3 3 3 3 4 4 19%	2629
November	1st to 10th	Night	21% 18% 6% 10% 5% 4 3 3 4 5% 21%	2715
	11th to 20th	Night	21% 20% 6% 12% 6% 5% 4 2 4 4 15%	2660
	21st to end	Night	24% 23% 6% 14% 7% 4 3 2 3 3 10%	2660
December	1st to 10th	Night	17% 26% 6% 15% 8% 4 3 3 3 3 11%	2660
	11th to 20th	Night	18% 22% 7% 14% 8% 6% 6% 3 3 3 12%	3408
	21st to end	Night	19% 19% 10% 18% 8% 4 3 3 2 3 12%	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	79% 6% 10% 5% 1	2209
	11th to 20th	Day	74% 6% 6% 11% 3	2346
	21st to end	Day	72% 4 7% 12% 5%	2880
February	1st to 10th	Day	70% 4 7% 11% 7%	1710
	11th to 20th	Day	70% 5% 7% 12% 6%	1672
	21st to end	Day	64% 5% 7% 17% 6% 1	1448
March	1st to 10th	Day	61% 5% 7% 18% 8% 1	3264
	11th to 20th	Day	63% 5% 7% 16% 8% 1	3480
	21st to end	Day	59% 6% 7% 18% 9% 2	3924
April	1st to 10th	Day	62% 5% 9% 12% 10% 2	2280
	11th to 20th	Day	56% 5% 10% 18% 10% 2	2329
	21st to end	Day	55% 6% 8% 16% 14% 2	2503
May	1st to 10th	Day	51% 9% 12% 19% 8% 1	4440
	11th to 20th	Day	47% 11% 13% 20% 8% 1	4402
	21st to end	Day	48% 7% 10% 19% 15% 1	4837
June	1st to 10th	Day	52% 8% 11% 19% 9% 1	2794
	11th to 20th	Day	47% 7% 10% 23% 11% 2	2850
	21st to end	Day	50% 8% 12% 20% 9% 1	2850
July	1st to 10th	Day	48% 7% 17% 23% 5%	4686
	11th to 20th	Day	46% 7% 17% 21% 9%	4619
	21st to end	Day	46% 7% 13% 26% 7%	4661
August	1st to 10th	Day	48% 7% 16% 24% 4	4323
	11th to 20th	Day	48% 8% 16% 21% 7%	4083
	21st to end	Day	44% 7% 12% 26% 10%	4351
September	1st to 10th	Day	49% 9% 14% 19% 9% 1	2280
	11th to 20th	Day	49% 8% 17% 20% 5%	2280
	21st to end	Day	55% 7% 12% 19% 7%	1986
October	1st to 10th	Day	58% 6% 10% 21% 5%	3160
	11th to 20th	Day	65% 5% 13% 13% 5%	3140
	21st to end	Day	70% 6% 13% 7% 4	3218
November	1st to 10th	Day	69% 6% 12% 9% 3	1566
	11th to 20th	Day	77% 5% 7% 8% 3	1520
	21st to end	Day	85% 4 6% 4 2	1520
December	1st to 10th	Day	79% 4 6% 8% 2	1520
	11th to 20th	Day	75% 7% 5% 11% 3	1784
	21st to end	Day	79% 4 7% 9% 1	2431
January	1st to 10th	Night	78% 6% 10% 5% 1	4748
	11th to 20th	Night	73% 6% 7% 10% 4	4603
	21st to end	Night	75% 7% 6% 8% 4 1	4774
February	1st to 10th	Night	66% 6% 8% 12% 8%	2470
	11th to 20th	Night	68% 5% 8% 14% 5%	2405
	21st to end	Night	67% 5% 8% 13% 7%	2004
March	1st to 10th	Night	58% 6% 10% 14% 11% 2	3588
	11th to 20th	Night	68% 6% 8% 12% 5% 1	3480
	21st to end	Night	54% 7% 9% 16% 11% 2	3707
April	1st to 10th	Night	60% 5% 7% 14% 12% 1	1900
	11th to 20th	Night	52% 6% 9% 20% 11% 1	1815
	21st to end	Night	52% 6% 8% 16% 15% 2	1677
May	1st to 10th	Night	50% 9% 14% 15% 10% 1	2520
	11th to 20th	Night	45% 9% 12% 22% 11% 1	2496
	21st to end	Night	46% 9% 13% 19% 13% 1	2739
June	1st to 10th	Night	52% 8% 12% 17% 10% 1	1382
	11th to 20th	Night	46% 7% 10% 20% 14% 3	1330
	21st to end	Night	44% 9% 14% 22% 11% 1	1330
July	1st to 10th	Night	46% 7% 14% 25% 7%	2175
	11th to 20th	Night	48% 7% 17% 21% 7%	2225
	21st to end	Night	44% 7% 15% 26% 9%	2651
August	1st to 10th	Night	43% 8% 17% 26% 5%	2580
	11th to 20th	Night	46% 7% 16% 24% 6%	2812
	21st to end	Night	45% 7% 15% 24% 7% 2	3272
September	1st to 10th	Night	45% 9% 16% 20% 9% 1	1900
	11th to 20th	Night	46% 8% 18% 22% 7%	1900
	21st to end	Night	50% 6% 14% 24% 6%	2190
October	1st to 10th	Night	54% 5% 12% 20% 8% 1	3800
	11th to 20th	Night	62% 5% 11% 19% 2	3779
	21st to end	Night	64% 5% 15% 9% 6% 1	4328
November	1st to 10th	Night	66% 6% 13% 13% 2	2715
	11th to 20th	Night	72% 7% 9% 9% 3	2660
	21st to end	Night	81% 5% 7% 6% 1	2660
December	1st to 10th	Night	79% 6% 7% 6% 2	2660
	11th to 20th	Night	78% 4 5% 10% 3	3408
	21st to end	Night	80% 4 4 8% 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	21% 22% 41% 12% 3 1	180
	11th to 20th	Day	17% 17% 37% 21% 6% 2	180
	21st to end	Day	18% 15% 36% 22% 9% 1	231
February	1st to 10th	Day	23% 24% 37% 11% 3 1	270
	11th to 20th	Day	22% 23% 40% 13% 3	270
	21st to end	Day	25% 22% 38% 13% 2	260
March	1st to 10th	Day	22% 19% 38% 16% 4 1	460
	11th to 20th	Day	24% 18% 35% 17% 5%	460
	21st to end	Day	24% 22% 35% 15% 4 1	506
April	1st to 10th	Day	30% 18% 28% 15% 7% 2	460
	11th to 20th	Day	28% 18% 28% 18% 6% 2	452
	21st to end	Day	28% 18% 32% 16% 5% 2	460
May	1st to 10th	Day	24% 17% 34% 17% 7% 1	463
	11th to 20th	Day	25% 18% 31% 18% 6% 2	487
	21st to end	Day	24% 18% 31% 22% 5%	529
June	1st to 10th	Day	25% 15% 34% 20% 6% 1	624
	11th to 20th	Day	21% 16% 34% 20% 7% 2	680
	21st to end	Day	20% 13% 31% 27% 8% 1	680
July	1st to 10th	Day	17% 14% 34% 25% 9% 1	671
	11th to 20th	Day	18% 12% 33% 26% 10% 1	634
	21st to end	Day	19% 10% 30% 28% 11% 3	532
August	1st to 10th	Day	20% 9% 32% 25% 11% 3	486
	11th to 20th	Day	20% 8% 25% 27% 13% 7%	479
	21st to end	Day	22% 12% 29% 20% 12% 5%	539
September	1st to 10th	Day	23% 11% 35% 19% 10% 2	490
	11th to 20th	Day	20% 11% 29% 26% 11% 3	490
	21st to end	Day	26% 15% 29% 17% 10% 2	490
October	1st to 10th	Day	30% 15% 25% 19% 9% 2	490
	11th to 20th	Day	36% 21% 25% 13% 4 1	490
	21st to end	Day	36% 14% 30% 15% 4	474
November	1st to 10th	Day	35% 22% 32% 8% 2	206
	11th to 20th	Day	31% 21% 33% 13% 2	180
	21st to end	Day	37% 22% 31% 7% 3 1	180
December	1st to 10th	Day	28% 15% 29% 21% 6% 1	180
	11th to 20th	Day	29% 16% 42% 9% 3 2	180
	21st to end	Day	29% 16% 34% 14% 5% 2	198
January	1st to 10th	Night	28% 13% 35% 19% 5%	950
	11th to 20th	Night	26% 14% 34% 21% 5%	858
	21st to end	Night	17% 12% 31% 28% 12% 1	836
February	1st to 10th	Night	16% 19% 34% 24% 6%	760
	11th to 20th	Night	22% 14% 35% 24% 5%	743
	21st to end	Night	19% 21% 35% 21% 5%	628
March	1st to 10th	Night	21% 20% 29% 23% 6%	760
	11th to 20th	Night	26% 19% 30% 20% 4 1	760
	21st to end	Night	22% 15% 34% 23% 6% 1	836
April	1st to 10th	Night	29% 13% 29% 22% 6% 1	760
	11th to 20th	Night	25% 17% 28% 22% 8%	691
	21st to end	Night	25% 11% 33% 24% 6% 1	537
May	1st to 10th	Night	21% 9% 36% 24% 9% 1	380
	11th to 20th	Night	24% 9% 30% 28% 8% 1	374
	21st to end	Night	25% 10% 32% 28% 5%	411
June	1st to 10th	Night	21% 10% 36% 26% 7%	380
	11th to 20th	Night	21% 9% 31% 32% 7%	380
	21st to end	Night	19% 6% 26% 36% 13%	380
July	1st to 10th	Night	16% 8% 29% 35% 10% 1	370
	11th to 20th	Night	14% 5% 31% 36% 13%	368
	21st to end	Night	15% 7% 23% 40% 13% 1	416
August	1st to 10th	Night	18% 5% 27% 32% 16% 2	423
	11th to 20th	Night	17% 5% 27% 27% 21% 2	564
	21st to end	Night	20% 9% 26% 29% 14% 3	710
September	1st to 10th	Night	22% 10% 31% 23% 13% 1	760
	11th to 20th	Night	24% 8% 27% 26% 13% 1	760
	21st to end	Night	26% 9% 26% 26% 11% 1	760
October	1st to 10th	Night	27% 13% 28% 23% 9% 1	760
	11th to 20th	Night	37% 13% 27% 16% 6% 1	760
	21st to end	Night	39% 12% 29% 17% 4	836
November	1st to 10th	Night	31% 15% 32% 15% 6% 1	779
	11th to 20th	Night	33% 17% 30% 15% 5%	760
	21st to end	Night	34% 18% 31% 14% 3 1	760
December	1st to 10th	Night	32% 17% 28% 16% 6% 1	760
	11th to 20th	Night	27% 17% 30% 19% 5% 2	836
	21st to end	Night	30% 17% 26% 19% 6% 1	1045

Page generated at 2024-11-07 06:55:48. Version ac07

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