Moosomin
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Moosomin clear sky chart from 2005-11-06 to 2026-07-01.

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	10% 8% 3 9% 5% 5% 5% 4 6% 7% 37%	142112
	Night	8% 9% 4 10% 6% 5% 5% 4 6% 7% 35%	139097
Transparency	Day	44% 6% 15% 25% 10% 1	141828
	Night	46% 6% 14% 23% 10% 1	138966
Seeing	Day	15% 11% 32% 27% 13% 3	18542
	Night	13% 9% 33% 32% 11% 1	28520

By Month

Percentage Cloud Cover NW (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	5% 10% 6% 16% 9% 10% 6% 5% 5% 8% 19%	4203
	11th to 20th	Day	3 9% 5% 13% 10% 10% 11% 9% 10% 7% 16%	4716
	21st to end	Day	6% 9% 5% 11% 6% 7% 6% 4 6% 7% 33%	5188
February	1st to 10th	Day	8% 14% 4 14% 9% 6% 5% 5% 6% 5% 23%	1680
	11th to 20th	Day	6% 11% 5% 12% 7% 7% 7% 5% 6% 7% 26%	1863
	21st to end	Day	5% 11% 4 14% 8% 6% 7% 5% 6% 8% 25%	1730
March	1st to 10th	Day	7% 13% 6% 14% 7% 6% 5% 4 6% 6% 26%	4600
	11th to 20th	Day	8% 14% 6% 16% 6% 5% 5% 4 5% 6% 25%	4814
	21st to end	Day	11% 12% 5% 15% 7% 5% 4 3 5% 6% 26%	5974
April	1st to 10th	Day	7% 11% 5% 7% 6% 5% 5% 3 6% 8% 37%	2520
	11th to 20th	Day	14% 14% 4 10% 6% 4 5% 4 6% 6% 28%	2639
	21st to end	Day	12% 9% 3 7% 5% 5% 5% 4 6% 8% 35%	2730
May	1st to 10th	Day	12% 8% 2 6% 4 4 5% 4 5% 7% 43%	8219
	11th to 20th	Day	22% 8% 3 7% 4 4 4 4 6% 7% 32%	8328
	21st to end	Day	12% 7% 2 6% 4 4 4 3 5% 7% 46%	9683
June	1st to 10th	Day	14% 7% 2 5% 5% 4 6% 4 6% 8% 39%	3150
	11th to 20th	Day	17% 7% 2 6% 5% 5% 5% 5% 8% 8% 31%	3150
	21st to end	Day	14% 6% 3 6% 4 4 5% 5% 7% 8% 37%	3150
July	1st to 10th	Day	7% 4 2 6% 5% 5% 6% 4 8% 9% 43%	6801
	11th to 20th	Day	10% 5% 2 6% 4 5% 5% 4 6% 8% 46%	6617
	21st to end	Day	7% 4 2 5% 4 4 5% 4 7% 9% 50%	6898
August	1st to 10th	Day	11% 5% 2 6% 4 4 5% 4 7% 9% 45%	4552
	11th to 20th	Day	9% 4 1 5% 3 4 4 4 6% 10% 49%	4356
	21st to end	Day	10% 5% 2 5% 3 4 5% 4 5% 8% 49%	4559
September	1st to 10th	Day	10% 5% 2 5% 4 4 4 4 5% 8% 49%	2400
	11th to 20th	Day	15% 7% 2 7% 4 4 4 3 5% 7% 41%	2275
	21st to end	Day	13% 6% 3 5% 4 4 4 3 4 7% 49%	2200
October	1st to 10th	Day	11% 9% 3 6% 4 4 3 4 5% 6% 45%	3472
	11th to 20th	Day	8% 8% 2 7% 3 4 4 3 6% 9% 46%	2927
	21st to end	Day	9% 13% 4 10% 4 4 4 4 6% 6% 36%	3190
November	1st to 10th	Day	16% 14% 5% 11% 5% 5% 4 3 4 6% 28%	1853
	11th to 20th	Day	9% 16% 4 12% 8% 5% 4 3 5% 6% 27%	1561
	21st to end	Day	7% 15% 5% 11% 7% 6% 6% 4 6% 6% 27%	1470
December	1st to 10th	Day	6% 11% 5% 18% 10% 9% 8% 4 5% 6% 19%	2360
	11th to 20th	Day	8% 14% 7% 14% 8% 7% 7% 4 5% 5% 21%	2709
	21st to end	Day	4 7% 4 14% 9% 5% 4 4 4 5% 39%	3575
January	1st to 10th	Night	6% 10% 6% 17% 9% 8% 7% 4 6% 6% 21%	8702
	11th to 20th	Night	4 9% 4 12% 8% 9% 12% 8% 9% 7% 18%	8212
	21st to end	Night	4 9% 5% 13% 7% 6% 6% 5% 7% 9% 27%	9026
February	1st to 10th	Night	9% 12% 5% 12% 8% 7% 6% 5% 6% 7% 25%	2940
	11th to 20th	Night	5% 10% 4 10% 7% 7% 5% 5% 7% 6% 33%	2664
	21st to end	Night	5% 10% 4 10% 7% 6% 5% 4 6% 8% 33%	2076
March	1st to 10th	Night	8% 10% 4 12% 5% 6% 5% 4 7% 8% 30%	5494
	11th to 20th	Night	8% 11% 4 11% 8% 5% 4 3 5% 7% 34%	5375
	21st to end	Night	9% 14% 5% 13% 6% 5% 4 3 5% 5% 30%	5212
April	1st to 10th	Night	4 10% 3 8% 4 4 4 5% 6% 8% 44%	2100
	11th to 20th	Night	13% 13% 4 9% 5% 4 4 3 6% 6% 32%	1932
	21st to end	Night	14% 8% 3 7% 5% 5% 5% 4 6% 7% 37%	1890
May	1st to 10th	Night	11% 7% 2 6% 4 4 4 4 5% 7% 46%	4725
	11th to 20th	Night	17% 8% 3 7% 5% 4 6% 4 6% 8% 32%	4549
	21st to end	Night	12% 6% 2 6% 3 3 5% 3 5% 6% 48%	4523
June	1st to 10th	Night	14% 6% 2 5% 5% 4 4 3 7% 6% 44%	1470
	11th to 20th	Night	15% 5% 2 5% 4 5% 5% 3 6% 9% 41%	1470
	21st to end	Night	13% 5% 2 6% 4 4 4 4 7% 6% 43%	1470
July	1st to 10th	Night	6% 3 2 5% 4 4 5% 4 7% 11% 50%	3180
	11th to 20th	Night	10% 4 2 5% 3 3 4 4 5% 8% 54%	3359
	21st to end	Night	7% 3 1 4 3 3 3 4 6% 9% 57%	3968
August	1st to 10th	Night	7% 5% 2 5% 4 4 5% 4 6% 8% 51%	2608
	11th to 20th	Night	4 4 2 6% 5% 4 4 4 6% 9% 53%	2703
	21st to end	Night	8% 4 1 5% 3 3 4 4 7% 8% 53%	3333
September	1st to 10th	Night	9% 4 2 6% 4 3 4 3 5% 7% 54%	2000
	11th to 20th	Night	13% 7% 2 5% 4 4 4 3 6% 7% 44%	2125
	21st to end	Night	12% 7% 2 5% 4 3 4 4 6% 7% 46%	2200
October	1st to 10th	Night	11% 9% 2 5% 3 3 4 3 4 6% 50%	3710
	11th to 20th	Night	8% 6% 3 6% 4 4 5% 5% 8% 9% 42%	4189
	21st to end	Night	8% 10% 4 8% 4 4 4 3 5% 7% 42%	4610
November	1st to 10th	Night	12% 13% 5% 10% 5% 4 5% 3 5% 6% 31%	2665
	11th to 20th	Night	9% 12% 6% 12% 9% 5% 5% 3 5% 6% 29%	3054
	21st to end	Night	8% 12% 5% 11% 7% 6% 5% 4 5% 8% 29%	3150
December	1st to 10th	Night	7% 12% 5% 14% 10% 9% 8% 6% 5% 6% 18%	5050
	11th to 20th	Night	8% 14% 4 13% 8% 7% 7% 5% 6% 6% 22%	5718
	21st to end	Night	5% 8% 3 13% 8% 7% 6% 4 6% 6% 34%	7645

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	61% 6% 11% 13% 9%	4203
	11th to 20th	Day	59% 6% 12% 16% 7%	4740
	21st to end	Day	48% 6% 14% 23% 9%	5188
February	1st to 10th	Day	60% 4 12% 16% 8% 1	1680
	11th to 20th	Day	54% 5% 10% 21% 10%	1871
	21st to end	Day	55% 6% 13% 18% 9%	1730
March	1st to 10th	Day	55% 6% 16% 16% 7%	4600
	11th to 20th	Day	57% 7% 13% 17% 6%	4816
	21st to end	Day	57% 6% 11% 17% 9%	5974
April	1st to 10th	Day	43% 6% 15% 23% 11% 1	2520
	11th to 20th	Day	54% 5% 12% 19% 8% 1	2639
	21st to end	Day	45% 7% 15% 24% 9%	2730
May	1st to 10th	Day	39% 5% 13% 28% 14% 1	8219
	11th to 20th	Day	50% 6% 10% 23% 10% 1	8332
	21st to end	Day	36% 6% 10% 26% 22% 1	9683
June	1st to 10th	Day	40% 8% 17% 25% 9% 2	3150
	11th to 20th	Day	46% 8% 16% 21% 9% 1	3150
	21st to end	Day	41% 9% 16% 26% 7% 1	3150
July	1st to 10th	Day	33% 9% 24% 28% 5%	6727
	11th to 20th	Day	34% 7% 19% 33% 7%	6536
	21st to end	Day	28% 8% 23% 31% 9% 2	6705
August	1st to 10th	Day	34% 7% 17% 30% 11%	4536
	11th to 20th	Day	29% 7% 21% 36% 7%	4398
	21st to end	Day	32% 7% 17% 36% 8%	4558
September	1st to 10th	Day	32% 6% 15% 33% 13% 1	2400
	11th to 20th	Day	42% 7% 15% 26% 10% 1	2275
	21st to end	Day	36% 4 13% 32% 14% 1	2200
October	1st to 10th	Day	40% 5% 15% 32% 8%	3472
	11th to 20th	Day	35% 4 17% 34% 10%	2927
	21st to end	Day	48% 4 12% 29% 8%	3190
November	1st to 10th	Day	58% 5% 11% 18% 7% 1	1853
	11th to 20th	Day	57% 5% 15% 13% 8% 1	1561
	21st to end	Day	56% 7% 13% 17% 6%	1470
December	1st to 10th	Day	65% 7% 13% 12% 4	2360
	11th to 20th	Day	64% 6% 13% 14% 3	2710
	21st to end	Day	47% 5% 6% 25% 14% 2	3575
January	1st to 10th	Night	62% 5% 9% 17% 7%	8703
	11th to 20th	Night	56% 8% 12% 17% 6%	8250
	21st to end	Night	51% 6% 16% 18% 8%	9026
February	1st to 10th	Night	55% 5% 12% 18% 9% 1	2940
	11th to 20th	Night	47% 5% 13% 22% 13% 1	2666
	21st to end	Night	47% 6% 12% 23% 12%	2076
March	1st to 10th	Night	49% 7% 19% 20% 6%	5494
	11th to 20th	Night	47% 6% 14% 23% 10%	5375
	21st to end	Night	55% 5% 10% 20% 10%	5212
April	1st to 10th	Night	37% 6% 13% 26% 17% 1	2100
	11th to 20th	Night	52% 5% 10% 21% 11% 1	1932
	21st to end	Night	44% 5% 13% 24% 12% 1	1890
May	1st to 10th	Night	36% 6% 11% 29% 18% 1	4725
	11th to 20th	Night	48% 7% 12% 23% 8% 2	4549
	21st to end	Night	35% 6% 10% 25% 23% 1	4526
June	1st to 10th	Night	39% 6% 15% 24% 13% 2	1470
	11th to 20th	Night	39% 7% 18% 21% 13% 1	1470
	21st to end	Night	38% 8% 18% 29% 7%	1470
July	1st to 10th	Night	27% 9% 27% 30% 7%	3145
	11th to 20th	Night	28% 6% 18% 41% 6%	3317
	21st to end	Night	24% 7% 23% 28% 15% 2	3856
August	1st to 10th	Night	28% 7% 20% 31% 13% 1	2600
	11th to 20th	Night	28% 6% 20% 37% 7% 1	2727
	21st to end	Night	27% 7% 18% 37% 11% 1	3333
September	1st to 10th	Night	30% 5% 13% 35% 16% 2	2000
	11th to 20th	Night	37% 8% 15% 27% 12% 1	2125
	21st to end	Night	38% 5% 12% 31% 13% 2	2200
October	1st to 10th	Night	36% 4 13% 32% 11% 4	3710
	11th to 20th	Night	35% 5% 13% 33% 12% 2	4189
	21st to end	Night	41% 4 13% 32% 10%	4610
November	1st to 10th	Night	53% 5% 12% 20% 8% 2	2665
	11th to 20th	Night	56% 6% 13% 18% 6% 1	3054
	21st to end	Night	52% 7% 16% 18% 6%	3150
December	1st to 10th	Night	65% 6% 13% 12% 4	5050
	11th to 20th	Night	60% 6% 12% 17% 5% 1	5716
	21st to end	Night	48% 5% 10% 20% 13% 3	7645

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	11% 10% 35% 31% 11% 3	330
	11th to 20th	Day	8% 13% 41% 29% 8% 1	330
	21st to end	Day	16% 12% 33% 28% 10% 1	363
February	1st to 10th	Day	14% 13% 38% 25% 9%	330
	11th to 20th	Day	11% 9% 36% 29% 12% 2	330
	21st to end	Day	8% 11% 33% 31% 14% 3	273
March	1st to 10th	Day	15% 10% 37% 25% 11% 2	330
	11th to 20th	Day	15% 13% 30% 29% 12% 2	330
	21st to end	Day	18% 10% 34% 24% 12% 2	532
April	1st to 10th	Day	14% 14% 38% 27% 6% 1	540
	11th to 20th	Day	21% 15% 30% 25% 8%	677
	21st to end	Day	16% 11% 31% 27% 14% 1	750
May	1st to 10th	Day	14% 12% 31% 28% 14% 2	753
	11th to 20th	Day	20% 11% 28% 22% 14% 4	775
	21st to end	Day	18% 8% 27% 27% 15% 4	844
June	1st to 10th	Day	16% 14% 29% 25% 12% 4	780
	11th to 20th	Day	18% 9% 33% 26% 11% 3	780
	21st to end	Day	14% 11% 28% 29% 15% 3	780
July	1st to 10th	Day	10% 7% 26% 33% 17% 6%	722
	11th to 20th	Day	9% 11% 30% 27% 17% 6%	718
	21st to end	Day	5% 7% 28% 37% 16% 7%	794
August	1st to 10th	Day	12% 6% 26% 34% 17% 6%	726
	11th to 20th	Day	10% 7% 28% 27% 22% 6%	715
	21st to end	Day	13% 7% 25% 33% 18% 4	739
September	1st to 10th	Day	12% 11% 35% 26% 12% 3	530
	11th to 20th	Day	19% 12% 27% 30% 11% 1	405
	21st to end	Day	18% 11% 32% 27% 11% 1	330
October	1st to 10th	Day	18% 12% 29% 25% 13% 2	330
	11th to 20th	Day	19% 12% 36% 23% 6% 4	330
	21st to end	Day	19% 12% 38% 24% 5% 2	363
November	1st to 10th	Day	26% 12% 31% 18% 11% 2	330
	11th to 20th	Day	18% 17% 35% 23% 6% 1	330
	21st to end	Day	15% 16% 37% 25% 6% 1	330
December	1st to 10th	Day	12% 12% 40% 22% 11% 3	330
	11th to 20th	Day	17% 12% 45% 19% 5% 1	330
	21st to end	Day	9% 9% 41% 24% 12% 4	363
January	1st to 10th	Night	10% 13% 38% 31% 7% 1	1050
	11th to 20th	Night	13% 14% 37% 27% 8% 1	1050
	21st to end	Night	11% 14% 41% 26% 7% 1	1155
February	1st to 10th	Night	14% 11% 36% 26% 11% 2	1050
	11th to 20th	Night	10% 9% 38% 30% 9% 3	926
	21st to end	Night	9% 9% 31% 35% 13% 3	692
March	1st to 10th	Night	16% 10% 32% 30% 11% 2	840
	11th to 20th	Night	10% 8% 40% 28% 12% 2	759
	21st to end	Night	16% 6% 33% 31% 12% 3	693
April	1st to 10th	Night	7% 10% 36% 37% 10%	630
	11th to 20th	Night	19% 10% 33% 30% 6% 1	623
	21st to end	Night	18% 6% 33% 33% 9%	630
May	1st to 10th	Night	15% 8% 27% 37% 12% 1	630
	11th to 20th	Night	16% 8% 30% 33% 13%	621
	21st to end	Night	22% 5% 27% 33% 13% 1	683
June	1st to 10th	Night	16% 6% 32% 33% 13% 1	630
	11th to 20th	Night	18% 4 34% 32% 12% 1	630
	21st to end	Night	16% 5% 29% 36% 14%	630
July	1st to 10th	Night	8% 4 26% 43% 19% 1	585
	11th to 20th	Night	8% 5% 32% 38% 16% 1	582
	21st to end	Night	5% 5% 28% 43% 17% 3	657
August	1st to 10th	Night	7% 5% 24% 45% 18% 1	597
	11th to 20th	Night	5% 5% 25% 38% 24% 2	594
	21st to end	Night	10% 5% 27% 42% 16% 1	660
September	1st to 10th	Night	11% 5% 29% 35% 16% 3	600
	11th to 20th	Night	14% 8% 32% 34% 12% 1	600
	21st to end	Night	14% 9% 30% 36% 11% 1	600
October	1st to 10th	Night	18% 10% 28% 32% 11% 1	668
	11th to 20th	Night	16% 12% 32% 29% 11% 1	975
	21st to end	Night	17% 12% 36% 27% 7% 1	1100
November	1st to 10th	Night	18% 13% 35% 25% 8% 1	1025
	11th to 20th	Night	14% 13% 40% 26% 7% 1	1050
	21st to end	Night	14% 15% 36% 29% 6% 1	1050
December	1st to 10th	Night	12% 11% 38% 27% 10% 3	1050
	11th to 20th	Night	16% 15% 34% 26% 9% 1	1050
	21st to end	Night	13% 8% 35% 31% 10% 2	1155

Page generated at 2026-06-28 00:10:49. Version ac07

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