Murdochville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Murdochville 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	14% 13% 4 10% 6% 6% 5% 4 5% 6% 26%	102070
	Night	13% 13% 4 11% 7% 6% 6% 4 5% 6% 25%	97742
Transparency	Day	58% 4 11% 18% 8% 1	105523
	Night	57% 5% 11% 19% 8% 1	102381
Seeing	Day	27% 21% 30% 15% 6% 1	16544
	Night	24% 20% 29% 19% 7% 1	24142

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	8% 13% 5% 13% 11% 13% 8% 6% 7% 5% 12%	2207
	11th to 20th	Day	6% 11% 4 17% 11% 10% 7% 6% 6% 7% 15%	2210
	21st to end	Day	3 8% 3 13% 8% 10% 8% 6% 8% 8% 26%	2759
February	1st to 10th	Day	6% 12% 4 11% 8% 8% 8% 5% 6% 8% 24%	1710
	11th to 20th	Day	7% 16% 7% 13% 8% 6% 5% 4 6% 6% 23%	1663
	21st to end	Day	5% 13% 4 12% 9% 7% 6% 5% 6% 7% 25%	1422
March	1st to 10th	Day	10% 15% 5% 10% 6% 6% 6% 5% 5% 8% 24%	3303
	11th to 20th	Day	13% 26% 8% 11% 6% 5% 5% 3 4 4 15%	3480
	21st to end	Day	17% 18% 6% 12% 5% 3 4 3 4 4 24%	3816
April	1st to 10th	Day	13% 19% 6% 13% 8% 6% 4 3 4 4 20%	2286
	11th to 20th	Day	12% 17% 5% 11% 5% 5% 4 3 5% 5% 27%	2442
	21st to end	Day	16% 17% 5% 10% 5% 4 4 2 3 4 27%	2470
May	1st to 10th	Day	14% 26% 5% 9% 5% 4 4 3 4 5% 20%	4319
	11th to 20th	Day	16% 13% 4 9% 5% 5% 5% 3 5% 6% 29%	4417
	21st to end	Day	20% 16% 4 8% 6% 5% 5% 3 5% 5% 22%	5185
June	1st to 10th	Day	22% 12% 4 8% 5% 4 4 4 6% 5% 26%	2850
	11th to 20th	Day	20% 8% 3 8% 5% 4 4 4 5% 7% 31%	2850
	21st to end	Day	24% 10% 3 8% 6% 5% 4 4 6% 6% 26%	2850
July	1st to 10th	Day	16% 8% 3 7% 5% 5% 5% 4 6% 8% 32%	4760
	11th to 20th	Day	13% 9% 3 7% 5% 6% 6% 5% 7% 8% 30%	4760
	21st to end	Day	12% 7% 2 6% 6% 5% 5% 4 6% 8% 38%	5101
August	1st to 10th	Day	16% 7% 3 8% 5% 5% 6% 4 6% 7% 31%	4141
	11th to 20th	Day	18% 9% 3 8% 7% 6% 6% 5% 6% 8% 25%	4045
	21st to end	Day	13% 9% 3 7% 4 5% 5% 4 5% 8% 38%	4532
September	1st to 10th	Day	21% 8% 3 6% 4 5% 5% 4 5% 5% 35%	2294
	11th to 20th	Day	19% 10% 3 6% 3 4 3 2 5% 6% 40%	2147
	21st to end	Day	15% 13% 4 8% 6% 5% 4 3 5% 5% 32%	2072
October	1st to 10th	Day	14% 16% 3 8% 6% 4 5% 3 4 6% 33%	1900
	11th to 20th	Day	18% 23% 5% 9% 5% 3 3 3 4 6% 22%	1900
	21st to end	Day	20% 20% 8% 9% 4 4 3 3 4 5% 19%	1922
November	1st to 10th	Day	14% 19% 8% 12% 6% 5% 5% 3 5% 4 18%	1565
	11th to 20th	Day	15% 16% 6% 18% 7% 5% 4 3 4 5% 16%	1600
	21st to end	Day	14% 18% 7% 18% 9% 4 3 3 5% 5% 15%	1600
December	1st to 10th	Day	12% 13% 6% 20% 11% 7% 6% 4 5% 6% 10%	1393
	11th to 20th	Day	7% 15% 5% 19% 12% 8% 7% 5% 6% 5% 11%	1668
	21st to end	Day	8% 13% 4 18% 13% 9% 6% 5% 5% 4 17%	2431
January	1st to 10th	Night	6% 12% 5% 16% 13% 13% 10% 6% 6% 4 9%	4748
	11th to 20th	Night	8% 13% 5% 13% 10% 11% 8% 5% 6% 6% 15%	4760
	21st to end	Night	4 7% 4 13% 9% 8% 10% 5% 6% 8% 26%	4883
February	1st to 10th	Night	6% 12% 4 10% 8% 8% 9% 6% 7% 7% 22%	2470
	11th to 20th	Night	8% 17% 5% 10% 8% 8% 8% 6% 7% 6% 18%	2403
	21st to end	Night	5% 13% 4 11% 9% 8% 8% 4 6% 6% 26%	2027
March	1st to 10th	Night	8% 12% 6% 9% 8% 6% 7% 5% 5% 5% 28%	3536
	11th to 20th	Night	12% 23% 6% 12% 7% 6% 5% 3 5% 4 17%	3479
	21st to end	Night	19% 16% 6% 10% 5% 4 4 3 4 5% 25%	3816
April	1st to 10th	Night	16% 16% 4 12% 6% 6% 6% 3 6% 5% 20%	1890
	11th to 20th	Night	15% 14% 3 7% 5% 5% 4 3 5% 7% 32%	1688
	21st to end	Night	18% 13% 5% 9% 4 3 4 3 5% 5% 31%	1710
May	1st to 10th	Night	18% 20% 4 7% 5% 5% 4 3 4 6% 26%	2628
	11th to 20th	Night	13% 11% 2 6% 4 5% 5% 5% 7% 8% 35%	2506
	21st to end	Night	15% 12% 5% 10% 7% 5% 6% 4 5% 7% 23%	2410
June	1st to 10th	Night	20% 9% 3 6% 5% 4 5% 4 5% 8% 30%	1330
	11th to 20th	Night	19% 9% 4 6% 4 5% 4 3 5% 7% 34%	1330
	21st to end	Night	21% 8% 3 7% 3 6% 6% 4 7% 6% 31%	1330
July	1st to 10th	Night	16% 8% 3 6% 3 5% 4 3 6% 7% 39%	2210
	11th to 20th	Night	12% 8% 2 7% 4 5% 5% 5% 7% 10% 35%	2210
	21st to end	Night	11% 7% 3 6% 3 4 4 4 6% 9% 44%	2430
August	1st to 10th	Night	14% 7% 3 6% 5% 5% 5% 5% 6% 8% 35%	2787
	11th to 20th	Night	14% 8% 3 7% 5% 4 5% 4 7% 7% 34%	2782
	21st to end	Night	16% 7% 2 5% 4 3 4 3 4 6% 46%	3124
September	1st to 10th	Night	18% 8% 3 7% 4 4 4 3 5% 6% 39%	1886
	11th to 20th	Night	16% 9% 3 7% 5% 4 4 3 5% 6% 38%	2030
	21st to end	Night	17% 10% 2 6% 4 3 4 3 4 6% 41%	2107
October	1st to 10th	Night	17% 10% 4 6% 5% 4 5% 4 5% 6% 35%	2280
	11th to 20th	Night	18% 17% 4 8% 5% 5% 4 4 5% 6% 24%	2280
	21st to end	Night	17% 17% 5% 9% 5% 6% 5% 4 5% 6% 21%	2670
November	1st to 10th	Night	16% 16% 8% 13% 5% 4 4 3 5% 5% 21%	2733
	11th to 20th	Night	14% 17% 6% 17% 7% 5% 4 3 5% 4 18%	2800
	21st to end	Night	14% 17% 7% 18% 9% 6% 6% 3 4 5% 13%	2800
December	1st to 10th	Night	12% 15% 5% 19% 13% 8% 6% 4 5% 4 10%	2902
	11th to 20th	Night	9% 14% 7% 17% 12% 9% 5% 4 5% 4 13%	3531
	21st to end	Night	11% 13% 6% 17% 11% 10% 6% 4 5% 5% 13%	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	68% 2 8% 15% 7%	2208
	11th to 20th	Day	65% 3 8% 16% 7%	2210
	21st to end	Day	50% 4 8% 21% 14% 2	2759
February	1st to 10th	Day	56% 5% 9% 17% 11% 2	1710
	11th to 20th	Day	62% 4 7% 15% 12% 1	1671
	21st to end	Day	54% 6% 6% 22% 10% 2	1422
March	1st to 10th	Day	59% 2 8% 20% 9% 1	3307
	11th to 20th	Day	72% 3 5% 10% 7% 1	3480
	21st to end	Day	64% 3 5% 17% 9% 2	3816
April	1st to 10th	Day	67% 4 4 12% 10% 2	2286
	11th to 20th	Day	58% 5% 7% 17% 12% 1	2442
	21st to end	Day	62% 2 7% 16% 12% 1	2470
May	1st to 10th	Day	68% 3 7% 13% 8% 1	4334
	11th to 20th	Day	56% 4 14% 18% 8%	4421
	21st to end	Day	63% 4 8% 15% 9% 1	5185
June	1st to 10th	Day	59% 4 10% 16% 10% 1	2850
	11th to 20th	Day	53% 5% 12% 18% 11% 1	2850
	21st to end	Day	60% 4 11% 17% 8%	2850
July	1st to 10th	Day	48% 5% 12% 23% 11%	4685
	11th to 20th	Day	49% 6% 17% 22% 6%	4679
	21st to end	Day	43% 5% 18% 24% 9%	4938
August	1st to 10th	Day	50% 6% 17% 22% 5%	4127
	11th to 20th	Day	55% 5% 17% 16% 6%	4084
	21st to end	Day	43% 5% 16% 27% 8% 1	4532
September	1st to 10th	Day	50% 5% 13% 22% 10%	2294
	11th to 20th	Day	47% 3 14% 26% 10%	2147
	21st to end	Day	54% 5% 10% 21% 9% 1	2072
October	1st to 10th	Day	52% 4 12% 21% 9% 1	3160
	11th to 20th	Day	62% 4 11% 16% 7%	3140
	21st to end	Day	58% 4 12% 18% 7% 1	3137
November	1st to 10th	Day	65% 5% 11% 13% 5%	1565
	11th to 20th	Day	69% 5% 9% 12% 5% 1	1600
	21st to end	Day	71% 4 10% 11% 4	1600
December	1st to 10th	Day	73% 6% 9% 11% 2	1393
	11th to 20th	Day	70% 6% 9% 12% 4	1668
	21st to end	Day	67% 4 10% 13% 6%	2431
January	1st to 10th	Night	71% 3 9% 14% 3	4748
	11th to 20th	Night	65% 4 8% 15% 8%	4760
	21st to end	Night	52% 4 8% 20% 11% 4	4883
February	1st to 10th	Night	54% 5% 8% 18% 11% 3	2470
	11th to 20th	Night	61% 5% 7% 17% 10% 1	2406
	21st to end	Night	53% 5% 7% 23% 11% 1	2027
March	1st to 10th	Night	57% 4 9% 19% 10% 1	3545
	11th to 20th	Night	69% 4 5% 15% 6% 1	3480
	21st to end	Night	62% 3 7% 16% 11% 2	3816
April	1st to 10th	Night	63% 6% 6% 13% 12% 1	1890
	11th to 20th	Night	51% 5% 8% 20% 14% 1	1688
	21st to end	Night	54% 3 8% 20% 12% 2	1710
May	1st to 10th	Night	59% 3 10% 19% 8% 1	2633
	11th to 20th	Night	47% 4 13% 24% 11%	2507
	21st to end	Night	59% 4 10% 19% 7%	2411
June	1st to 10th	Night	54% 3 12% 21% 10%	1330
	11th to 20th	Night	49% 3 15% 19% 13% 1	1330
	21st to end	Night	53% 6% 14% 19% 8% 1	1330
July	1st to 10th	Night	41% 7% 17% 21% 14%	2175
	11th to 20th	Night	40% 5% 23% 28% 5%	2168
	21st to end	Night	36% 6% 25% 22% 11%	2353
August	1st to 10th	Night	45% 6% 21% 22% 5%	2776
	11th to 20th	Night	46% 6% 23% 20% 5%	2809
	21st to end	Night	38% 4 16% 30% 11%	3124
September	1st to 10th	Night	45% 5% 15% 26% 9%	1886
	11th to 20th	Night	45% 6% 15% 24% 10%	2030
	21st to end	Night	43% 5% 13% 26% 12% 1	2107
October	1st to 10th	Night	52% 4 10% 25% 8% 1	3800
	11th to 20th	Night	54% 5% 12% 20% 10%	3779
	21st to end	Night	55% 8% 13% 18% 5% 1	4407
November	1st to 10th	Night	61% 7% 11% 15% 5%	2733
	11th to 20th	Night	67% 5% 10% 13% 5%	2800
	21st to end	Night	71% 6% 10% 11% 2 1	2800
December	1st to 10th	Night	72% 6% 8% 11% 3	2902
	11th to 20th	Night	71% 4 6% 14% 5%	3532
	21st to end	Night	71% 3 10% 12% 4	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	28% 22% 31% 14% 3 1	180
	11th to 20th	Day	30% 28% 24% 14% 4	180
	21st to end	Day	17% 27% 37% 13% 5% 1	238
February	1st to 10th	Day	20% 29% 30% 14% 5% 2	370
	11th to 20th	Day	23% 31% 30% 11% 5% 1	366
	21st to end	Day	21% 27% 32% 14% 5% 1	312
March	1st to 10th	Day	26% 25% 35% 9% 3 1	460
	11th to 20th	Day	27% 23% 29% 13% 6% 2	460
	21st to end	Day	30% 24% 32% 9% 4 2	506
April	1st to 10th	Day	35% 25% 26% 10% 3 1	460
	11th to 20th	Day	30% 26% 29% 11% 4 1	452
	21st to end	Day	32% 21% 29% 14% 2 2	460
May	1st to 10th	Day	31% 21% 27% 13% 6% 1	586
	11th to 20th	Day	30% 19% 27% 17% 7% 1	674
	21st to end	Day	35% 21% 27% 13% 4 1	735
June	1st to 10th	Day	31% 16% 30% 18% 5% 1	680
	11th to 20th	Day	28% 17% 27% 18% 9% 1	680
	21st to end	Day	29% 17% 27% 20% 6% 2	680
July	1st to 10th	Day	22% 14% 36% 18% 9% 1	670
	11th to 20th	Day	16% 16% 37% 23% 7% 1	668
	21st to end	Day	21% 12% 31% 26% 9% 2	740
August	1st to 10th	Day	21% 15% 35% 20% 7% 1	509
	11th to 20th	Day	21% 13% 33% 23% 8% 2	479
	21st to end	Day	20% 17% 35% 17% 9% 2	539
September	1st to 10th	Day	26% 19% 31% 17% 6% 2	490
	11th to 20th	Day	29% 18% 31% 16% 3 4	490
	21st to end	Day	27% 24% 28% 13% 7% 2	480
October	1st to 10th	Day	24% 25% 28% 12% 8% 2	390
	11th to 20th	Day	31% 25% 23% 12% 8% 1	390
	21st to end	Day	35% 23% 22% 13% 6% 1	429
November	1st to 10th	Day	32% 26% 27% 12% 3 1	395
	11th to 20th	Day	31% 24% 28% 13% 3 2	400
	21st to end	Day	34% 24% 28% 10% 3 2	400
December	1st to 10th	Day	27% 23% 32% 13% 4 2	218
	11th to 20th	Day	28% 31% 29% 11% 1	180
	21st to end	Day	31% 27% 28% 13% 2	198
January	1st to 10th	Night	22% 22% 35% 16% 4 1	850
	11th to 20th	Night	24% 24% 31% 16% 5%	850
	21st to end	Night	16% 28% 31% 18% 7% 1	855
February	1st to 10th	Night	17% 28% 33% 15% 6% 1	760
	11th to 20th	Night	23% 27% 29% 16% 5% 1	743
	21st to end	Night	18% 27% 33% 15% 6% 2	628
March	1st to 10th	Night	22% 24% 34% 13% 6% 1	760
	11th to 20th	Night	24% 24% 27% 17% 7% 1	760
	21st to end	Night	25% 20% 31% 17% 5% 1	836
April	1st to 10th	Night	30% 19% 31% 15% 5%	607
	11th to 20th	Night	25% 22% 28% 18% 7% 1	564
	21st to end	Night	30% 16% 28% 18% 7% 1	570
May	1st to 10th	Night	29% 13% 27% 22% 9% 1	570
	11th to 20th	Night	28% 14% 24% 23% 10% 1	562
	21st to end	Night	23% 18% 34% 20% 5%	420
June	1st to 10th	Night	24% 12% 27% 29% 8% 1	380
	11th to 20th	Night	24% 11% 29% 26% 10%	380
	21st to end	Night	27% 10% 24% 27% 10% 1	380
July	1st to 10th	Night	19% 8% 37% 22% 13% 1	370
	11th to 20th	Night	15% 7% 33% 35% 10%	368
	21st to end	Night	16% 9% 28% 35% 12%	432
August	1st to 10th	Night	19% 7% 31% 32% 11%	568
	11th to 20th	Night	20% 8% 27% 32% 13% 1	562
	21st to end	Night	18% 11% 29% 26% 14% 2	627
September	1st to 10th	Night	21% 16% 30% 24% 8%	570
	11th to 20th	Night	23% 13% 32% 21% 9% 1	700
	21st to end	Night	24% 18% 28% 21% 7% 1	760
October	1st to 10th	Night	25% 18% 30% 19% 7% 1	760
	11th to 20th	Night	29% 20% 26% 16% 9% 1	760
	21st to end	Night	29% 23% 25% 16% 7% 1	847
November	1st to 10th	Night	33% 21% 27% 14% 4	880
	11th to 20th	Night	30% 23% 27% 14% 5% 1	900
	21st to end	Night	30% 23% 28% 13% 5%	900
December	1st to 10th	Night	25% 26% 30% 13% 5% 1	878
	11th to 20th	Night	29% 26% 29% 13% 4 1	850
	21st to end	Night	27% 24% 26% 17% 4 2	935

Page generated at 2024-12-03 06:45:13. Version ac07

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