Chibougamau
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Chibougamau clear sky chart from 2005-11-06 to 2024-04-25.

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% 5% 10% 8% 4 6% 5% 5% 6% 21%	83399
	Night	16% 14% 6% 11% 9% 5% 6% 5% 5% 5% 19%	85687
Transparency	Day	64% 6% 9% 14% 7% 1	83099
	Night	67% 6% 9% 13% 5%	85523
Seeing	Day	24% 13% 30% 22% 10% 2	14627
	Night	24% 11% 29% 26% 10% 1	22847

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% 16% 8% 17% 12% 8% 6% 5% 4 4 8%	2517
	11th to 20th	Day	11% 13% 6% 14% 16% 9% 10% 6% 5% 5% 6%	2520
	21st to end	Day	7% 13% 6% 19% 10% 5% 7% 7% 5% 6% 15%	2772
February	1st to 10th	Day	6% 11% 6% 13% 13% 7% 9% 9% 7% 6% 13%	1565
	11th to 20th	Day	10% 15% 6% 16% 11% 5% 7% 9% 6% 6% 10%	1663
	21st to end	Day	8% 15% 8% 10% 11% 5% 8% 6% 6% 7% 16%	1556
March	1st to 10th	Day	17% 14% 5% 9% 7% 4 4 5% 5% 5% 25%	3116
	11th to 20th	Day	10% 16% 7% 14% 13% 6% 6% 5% 4 4 15%	3315
	21st to end	Day	9% 14% 7% 14% 10% 4 6% 5% 5% 5% 21%	4130
April	1st to 10th	Day	17% 15% 8% 10% 8% 4 4 4 4 5% 23%	2280
	11th to 20th	Day	17% 10% 5% 10% 6% 4 6% 5% 5% 6% 26%	2278
	21st to end	Day	17% 13% 5% 10% 6% 3 5% 4 4 6% 27%	2527
May	1st to 10th	Day	17% 11% 5% 8% 7% 4 4 4 4 7% 29%	2520
	11th to 20th	Day	18% 8% 3 7% 7% 4 5% 5% 5% 6% 32%	2478
	21st to end	Day	19% 9% 3 6% 6% 4 6% 5% 5% 7% 29%	2756
June	1st to 10th	Day	22% 9% 4 7% 7% 3 5% 4 5% 7% 28%	2700
	11th to 20th	Day	17% 7% 4 7% 7% 4 6% 5% 7% 7% 30%	2874
	21st to end	Day	19% 7% 3 7% 7% 4 7% 5% 6% 7% 28%	2880
July	1st to 10th	Day	18% 8% 4 6% 6% 5% 6% 6% 6% 8% 27%	2767
	11th to 20th	Day	17% 9% 3 7% 7% 4 6% 6% 7% 8% 28%	2530
	21st to end	Day	19% 9% 3 7% 7% 5% 6% 6% 6% 8% 24%	2744
August	1st to 10th	Day	21% 10% 5% 8% 8% 5% 7% 5% 5% 7% 19%	2506
	11th to 20th	Day	20% 9% 4 8% 7% 4 5% 5% 6% 7% 25%	2481
	21st to end	Day	20% 9% 4 7% 6% 4 5% 6% 5% 7% 27%	2387
September	1st to 10th	Day	22% 10% 3 8% 6% 3 5% 4 4 6% 28%	2160
	11th to 20th	Day	22% 12% 3 8% 6% 4 5% 5% 5% 7% 23%	2119
	21st to end	Day	25% 13% 3 7% 6% 3 4 4 3 5% 27%	1976
October	1st to 10th	Day	24% 12% 6% 7% 6% 3 4 4 3 6% 26%	1800
	11th to 20th	Day	31% 20% 6% 9% 6% 3 4 4 3 2 12%	1724
	21st to end	Day	28% 18% 7% 11% 7% 4 4 2 2 5% 12%	1782
November	1st to 10th	Day	22% 24% 8% 12% 7% 3 3 3 3 3 12%	1595
	11th to 20th	Day	22% 22% 9% 13% 9% 4 3 3 2 3 9%	1520
	21st to end	Day	20% 24% 10% 14% 9% 4 5% 3 3 3 5%	1387
December	1st to 10th	Day	16% 22% 9% 15% 9% 6% 6% 5% 3 3 8%	1330
	11th to 20th	Day	17% 15% 6% 14% 10% 5% 7% 5% 5% 4 12%	1668
	21st to end	Day	13% 17% 10% 16% 12% 6% 7% 5% 4 4 7%	2476
January	1st to 10th	Night	13% 17% 8% 14% 11% 7% 8% 5% 4 4 8%	4429
	11th to 20th	Night	10% 15% 6% 16% 13% 6% 9% 6% 5% 5% 8%	4440
	21st to end	Night	7% 14% 10% 16% 10% 6% 8% 7% 6% 4 13%	4884
February	1st to 10th	Night	8% 12% 6% 10% 10% 7% 11% 8% 8% 6% 14%	2613
	11th to 20th	Night	9% 17% 7% 12% 11% 6% 8% 8% 5% 6% 12%	2403
	21st to end	Night	8% 14% 6% 12% 11% 5% 6% 8% 6% 6% 18%	1897
March	1st to 10th	Night	14% 15% 5% 9% 7% 4 6% 7% 5% 5% 23%	3724
	11th to 20th	Night	12% 18% 7% 15% 10% 5% 6% 5% 4 4 14%	3641
	21st to end	Night	13% 15% 6% 12% 7% 4 5% 5% 5% 5% 23%	3501
April	1st to 10th	Night	18% 14% 6% 9% 8% 4 5% 4 4 5% 25%	1900
	11th to 20th	Night	13% 12% 5% 9% 7% 4 5% 5% 4 6% 29%	1849
	21st to end	Night	18% 10% 5% 8% 7% 3 4 4 5% 4 33%	1549
May	1st to 10th	Night	18% 11% 3 7% 7% 3 4 4 5% 5% 32%	1440
	11th to 20th	Night	16% 10% 5% 7% 6% 3 5% 5% 5% 5% 33%	1415
	21st to end	Night	22% 10% 3 7% 5% 3 5% 4 4 7% 31%	1514
June	1st to 10th	Night	22% 9% 3 7% 6% 3 4 5% 5% 6% 30%	1260
	11th to 20th	Night	18% 7% 4 8% 5% 4 6% 6% 6% 7% 31%	1080
	21st to end	Night	17% 6% 2 6% 5% 4 5% 5% 6% 6% 38%	1080
July	1st to 10th	Night	21% 6% 3 7% 5% 3 4 5% 6% 8% 32%	1189
	11th to 20th	Night	15% 6% 3 5% 6% 4 5% 5% 6% 8% 37%	1428
	21st to end	Night	18% 8% 3 7% 6% 3 5% 5% 6% 7% 30%	1574
August	1st to 10th	Night	21% 8% 3 5% 6% 3 5% 6% 6% 8% 29%	1432
	11th to 20th	Night	16% 9% 4 6% 7% 4 4 5% 6% 8% 31%	1420
	21st to end	Night	20% 9% 4 8% 6% 4 5% 5% 5% 6% 30%	1947
September	1st to 10th	Night	22% 8% 3 6% 6% 3 4 3 4 6% 34%	1800
	11th to 20th	Night	23% 11% 3 7% 6% 3 4 4 5% 6% 28%	1840
	21st to end	Night	21% 11% 4 8% 6% 3 4 4 4 5% 31%	1981
October	1st to 10th	Night	21% 11% 4 6% 5% 3 5% 5% 5% 6% 29%	2160
	11th to 20th	Night	28% 17% 6% 9% 6% 3 4 4 4 4 15%	2236
	21st to end	Night	29% 18% 6% 9% 6% 3 4 3 4 4 14%	2574
November	1st to 10th	Night	25% 21% 7% 12% 7% 4 4 3 3 3 10%	2483
	11th to 20th	Night	19% 20% 8% 13% 10% 4 6% 4 4 3 10%	2660
	21st to end	Night	18% 23% 10% 15% 11% 5% 5% 4 2 3 6%	2791
December	1st to 10th	Night	16% 21% 8% 16% 11% 4 6% 4 3 3 7%	2850
	11th to 20th	Night	16% 17% 7% 11% 11% 7% 7% 6% 5% 4 10%	3531
	21st to end	Night	13% 15% 8% 19% 13% 6% 6% 4 4 3 9%	5172

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	80% 3 6% 9% 1	2518
	11th to 20th	Day	80% 5% 4 7% 3	2520
	21st to end	Day	69% 4 8% 11% 8%	2772
February	1st to 10th	Day	67% 5% 6% 13% 8%	1565
	11th to 20th	Day	72% 6% 8% 10% 5%	1672
	21st to end	Day	66% 5% 7% 13% 8%	1556
March	1st to 10th	Day	61% 4 5% 17% 12% 1	3119
	11th to 20th	Day	70% 6% 6% 12% 5% 1	3315
	21st to end	Day	63% 6% 7% 11% 11% 2	4130
April	1st to 10th	Day	64% 5% 9% 13% 8% 1	2280
	11th to 20th	Day	58% 6% 9% 16% 10% 1	2278
	21st to end	Day	58% 7% 7% 15% 13% 1	2527
May	1st to 10th	Day	55% 6% 8% 19% 11% 1	2520
	11th to 20th	Day	52% 6% 10% 19% 11% 2	2482
	21st to end	Day	53% 7% 11% 19% 10% 1	2756
June	1st to 10th	Day	55% 6% 8% 19% 11%	2700
	11th to 20th	Day	51% 8% 10% 17% 12% 2	2874
	21st to end	Day	53% 9% 10% 18% 10%	2880
July	1st to 10th	Day	52% 9% 14% 19% 5%	2693
	11th to 20th	Day	51% 8% 15% 20% 6%	2454
	21st to end	Day	56% 10% 15% 15% 4	2591
August	1st to 10th	Day	63% 9% 14% 13% 1	2492
	11th to 20th	Day	56% 10% 15% 14% 5%	2481
	21st to end	Day	55% 8% 12% 21% 4	2387
September	1st to 10th	Day	56% 6% 13% 16% 8%	2160
	11th to 20th	Day	59% 8% 12% 16% 4	2119
	21st to end	Day	60% 6% 12% 18% 4	1976
October	1st to 10th	Day	61% 6% 11% 14% 7% 1	1800
	11th to 20th	Day	79% 5% 7% 7% 1 1	1724
	21st to end	Day	77% 5% 8% 7% 3 1	1782
November	1st to 10th	Day	79% 5% 8% 7% 2 1	1595
	11th to 20th	Day	83% 4 6% 5% 1	1520
	21st to end	Day	88% 3 6% 3	1387
December	1st to 10th	Day	84% 3 4 8% 1	1330
	11th to 20th	Day	75% 5% 5% 11% 4 1	1668
	21st to end	Day	80% 5% 5% 5% 4 1	2476
January	1st to 10th	Night	80% 4 7% 8% 1	4429
	11th to 20th	Night	78% 5% 6% 8% 3	4440
	21st to end	Night	70% 5% 6% 13% 6%	4884
February	1st to 10th	Night	66% 6% 8% 12% 8%	2613
	11th to 20th	Night	72% 6% 7% 10% 4	2405
	21st to end	Night	64% 6% 7% 15% 7%	1897
March	1st to 10th	Night	61% 6% 6% 17% 10% 1	3734
	11th to 20th	Night	71% 6% 6% 12% 5%	3642
	21st to end	Night	61% 5% 9% 17% 7% 1	3501
April	1st to 10th	Night	61% 5% 9% 14% 9% 2	1900
	11th to 20th	Night	55% 6% 9% 20% 9% 1	1849
	21st to end	Night	55% 5% 9% 17% 13% 2	1549
May	1st to 10th	Night	54% 5% 10% 16% 12% 3	1440
	11th to 20th	Night	51% 6% 10% 17% 13% 1	1416
	21st to end	Night	54% 5% 7% 19% 15% 1	1515
June	1st to 10th	Night	53% 5% 10% 18% 12% 1	1260
	11th to 20th	Night	49% 9% 9% 19% 13% 2	1080
	21st to end	Night	45% 8% 13% 24% 9%	1080
July	1st to 10th	Night	49% 7% 15% 22% 7%	1154
	11th to 20th	Night	42% 8% 16% 26% 8%	1381
	21st to end	Night	54% 8% 13% 22% 2	1486
August	1st to 10th	Night	51% 11% 20% 17% 1	1422
	11th to 20th	Night	49% 9% 19% 17% 6%	1420
	21st to end	Night	54% 8% 15% 20% 3	1947
September	1st to 10th	Night	54% 5% 11% 21% 9%	1800
	11th to 20th	Night	55% 8% 15% 17% 5%	1840
	21st to end	Night	56% 5% 14% 20% 5%	1981
October	1st to 10th	Night	56% 8% 13% 16% 7% 1	2160
	11th to 20th	Night	74% 5% 8% 11% 2 1	2236
	21st to end	Night	76% 5% 7% 8% 4 1	2574
November	1st to 10th	Night	79% 5% 5% 7% 3	2483
	11th to 20th	Night	81% 4 8% 6% 1	2660
	21st to end	Night	87% 3 6% 4	2791
December	1st to 10th	Night	83% 4 6% 7% 1	2850
	11th to 20th	Night	76% 5% 7% 10% 3	3532
	21st to end	Night	79% 4 7% 6% 3 1	5172

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	14% 15% 39% 27% 3 1	180
	11th to 20th	Day	19% 11% 34% 18% 14% 3	180
	21st to end	Day	16% 10% 31% 28% 13% 2	198
February	1st to 10th	Day	7% 19% 40% 27% 6% 1	202
	11th to 20th	Day	17% 12% 41% 22% 7% 1	270
	21st to end	Day	18% 15% 40% 19% 7% 1	368
March	1st to 10th	Day	17% 15% 32% 25% 10% 1	460
	11th to 20th	Day	20% 14% 34% 22% 9% 2	460
	21st to end	Day	24% 14% 30% 25% 5% 2	506
April	1st to 10th	Day	22% 15% 31% 20% 10% 3	460
	11th to 20th	Day	22% 15% 29% 25% 6% 3	452
	21st to end	Day	22% 15% 36% 18% 7% 2	437
May	1st to 10th	Day	23% 13% 33% 21% 9% 2	423
	11th to 20th	Day	23% 12% 26% 24% 12% 3	447
	21st to end	Day	22% 14% 32% 23% 8%	516
June	1st to 10th	Day	27% 10% 29% 23% 8% 2	630
	11th to 20th	Day	21% 13% 30% 23% 11% 2	804
	21st to end	Day	21% 8% 27% 29% 13% 2	810
July	1st to 10th	Day	22% 10% 28% 26% 11% 2	688
	11th to 20th	Day	22% 9% 24% 28% 14% 3	453
	21st to end	Day	23% 7% 26% 23% 15% 6%	488
August	1st to 10th	Day	24% 11% 23% 23% 14% 4	446
	11th to 20th	Day	23% 9% 23% 25% 14% 7%	439
	21st to end	Day	24% 10% 26% 21% 11% 7%	495
September	1st to 10th	Day	28% 11% 28% 20% 10% 3	450
	11th to 20th	Day	24% 14% 30% 22% 8% 2	450
	21st to end	Day	30% 12% 26% 18% 10% 3	450
October	1st to 10th	Day	28% 14% 26% 19% 10% 2	450
	11th to 20th	Day	36% 17% 22% 16% 6% 2	412
	21st to end	Day	34% 15% 28% 17% 6% 1	396
November	1st to 10th	Day	38% 16% 32% 11% 2	289
	11th to 20th	Day	33% 18% 28% 14% 7%	180
	21st to end	Day	37% 13% 32% 12% 5% 1	180
December	1st to 10th	Day	26% 12% 23% 21% 16% 3	180
	11th to 20th	Day	24% 22% 27% 14% 11% 2	180
	21st to end	Day	20% 15% 34% 22% 7% 3	198
January	1st to 10th	Night	21% 11% 33% 26% 9% 1	760
	11th to 20th	Night	19% 14% 34% 23% 9% 1	760
	21st to end	Night	14% 8% 31% 32% 14% 1	836
February	1st to 10th	Night	12% 11% 32% 34% 9% 2	760
	11th to 20th	Night	19% 11% 30% 30% 10% 1	743
	21st to end	Night	17% 13% 33% 25% 11% 1	628
March	1st to 10th	Night	16% 13% 31% 30% 9% 1	760
	11th to 20th	Night	19% 13% 31% 28% 8% 1	760
	21st to end	Night	22% 12% 35% 25% 6% 1	836
April	1st to 10th	Night	24% 11% 30% 26% 9%	760
	11th to 20th	Night	19% 12% 32% 26% 10%	725
	21st to end	Night	24% 7% 34% 26% 9% 1	439
May	1st to 10th	Night	27% 4 31% 28% 10% 1	360
	11th to 20th	Night	20% 8% 34% 25% 11% 2	354
	21st to end	Night	26% 9% 29% 28% 7%	389
June	1st to 10th	Night	25% 7% 30% 28% 10%	360
	11th to 20th	Night	20% 7% 30% 31% 11%	360
	21st to end	Night	20% 7% 24% 35% 13% 1	360
July	1st to 10th	Night	25% 6% 27% 31% 9% 1	350
	11th to 20th	Night	18% 3 26% 36% 15% 1	348
	21st to end	Night	24% 5% 18% 36% 17% 1	394
August	1st to 10th	Night	24% 4 22% 27% 22% 2	358
	11th to 20th	Night	20% 6% 21% 30% 21% 2	356
	21st to end	Night	24% 8% 22% 26% 15% 3	759
September	1st to 10th	Night	28% 6% 25% 27% 14% 1	720
	11th to 20th	Night	29% 10% 25% 26% 8% 2	720
	21st to end	Night	27% 10% 28% 25% 10% 1	720
October	1st to 10th	Night	25% 12% 30% 23% 8% 1	720
	11th to 20th	Night	37% 10% 26% 20% 5% 2	720
	21st to end	Night	39% 10% 25% 19% 7% 1	792
November	1st to 10th	Night	36% 16% 25% 16% 6% 1	740
	11th to 20th	Night	28% 15% 32% 18% 6%	760
	21st to end	Night	28% 17% 30% 18% 6% 1	823
December	1st to 10th	Night	25% 11% 32% 22% 9% 1	850
	11th to 20th	Night	22% 13% 32% 21% 9% 2	850
	21st to end	Night	24% 13% 31% 23% 8% 1	917

Page generated at 2024-04-22 09:25:41. Version ac07

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