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 2025-02-25.

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	10% 8% 3 9% 6% 5% 5% 4 6% 7% 36%	112226
	Night	8% 9% 4 10% 6% 5% 5% 4 6% 7% 35%	115190
Transparency	Day	44% 7% 15% 25% 8% 1	111984
	Night	46% 6% 14% 23% 9% 1	115079
Seeing	Day	14% 10% 31% 28% 13% 3	16579
	Night	13% 9% 33% 32% 11% 1	26741

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% 11% 6% 17% 9% 11% 6% 5% 6% 7% 17%	3243
	11th to 20th	Day	3 7% 4 12% 10% 9% 10% 11% 11% 7% 16%	3616
	21st to end	Day	6% 10% 6% 14% 7% 7% 6% 4 4 6% 30%	4004
February	1st to 10th	Day	8% 14% 4 13% 9% 7% 5% 5% 6% 5% 24%	1600
	11th to 20th	Day	6% 11% 5% 12% 7% 7% 7% 5% 6% 8% 27%	1772
	21st to end	Day	6% 12% 4 14% 8% 5% 7% 5% 6% 8% 25%	1610
March	1st to 10th	Day	9% 14% 6% 12% 8% 7% 6% 4 5% 6% 24%	3130
	11th to 20th	Day	7% 11% 5% 16% 7% 6% 6% 4 5% 6% 28%	3288
	21st to end	Day	7% 11% 5% 14% 7% 5% 5% 4 7% 7% 29%	4083
April	1st to 10th	Day	7% 11% 4 7% 6% 5% 5% 3 6% 8% 37%	2280
	11th to 20th	Day	14% 14% 4 9% 5% 4 5% 4 5% 7% 28%	2385
	21st to end	Day	13% 9% 3 7% 5% 5% 5% 4 6% 8% 35%	2470
May	1st to 10th	Day	19% 9% 2 6% 4 4 4 3 5% 6% 36%	4425
	11th to 20th	Day	16% 9% 3 8% 5% 5% 5% 4 6% 6% 32%	4469
	21st to end	Day	15% 8% 3 7% 5% 5% 5% 4 6% 7% 35%	5173
June	1st to 10th	Day	14% 6% 2 5% 5% 4 6% 4 6% 8% 40%	2850
	11th to 20th	Day	18% 7% 2 6% 5% 5% 5% 4 8% 8% 32%	2850
	21st to end	Day	13% 6% 2 6% 4 4 5% 5% 7% 9% 38%	2850
July	1st to 10th	Day	8% 4 2 6% 5% 5% 6% 4 8% 9% 44%	4750
	11th to 20th	Day	6% 4 2 5% 4 4 5% 4 6% 9% 53%	4623
	21st to end	Day	5% 3 1 4 4 4 5% 5% 7% 9% 52%	4802
August	1st to 10th	Day	11% 5% 2 5% 4 4 5% 4 7% 9% 45%	4412
	11th to 20th	Day	9% 4 1 5% 3 4 4 4 6% 10% 50%	4220
	21st to end	Day	11% 5% 2 5% 3 4 5% 4 5% 7% 49%	4419
September	1st to 10th	Day	11% 5% 2 5% 4 3 4 4 5% 8% 49%	2280
	11th to 20th	Day	14% 7% 2 7% 4 4 4 3 5% 7% 43%	2161
	21st to end	Day	14% 6% 3 5% 4 4 4 3 4 7% 47%	2090
October	1st to 10th	Day	11% 9% 3 6% 4 4 3 4 5% 6% 44%	3366
	11th to 20th	Day	7% 7% 2 7% 3 4 4 3 6% 9% 47%	2837
	21st to end	Day	9% 13% 4 10% 5% 4 4 4 6% 6% 35%	3091
November	1st to 10th	Day	16% 14% 5% 10% 5% 5% 4 3 4 5% 28%	1763
	11th to 20th	Day	10% 16% 4 13% 8% 5% 4 3 5% 6% 26%	1487
	21st to end	Day	8% 16% 5% 11% 7% 6% 6% 4 6% 6% 27%	1400
December	1st to 10th	Day	6% 11% 5% 18% 10% 9% 8% 4 5% 6% 19%	2290
	11th to 20th	Day	8% 14% 7% 14% 8% 7% 7% 4 4 5% 21%	2639
	21st to end	Day	4 7% 4 14% 9% 5% 4 4 4 5% 40%	3498
January	1st to 10th	Night	5% 10% 6% 17% 10% 8% 7% 4 6% 7% 20%	6718
	11th to 20th	Night	5% 8% 4 12% 8% 9% 11% 8% 10% 7% 18%	6302
	21st to end	Night	5% 12% 6% 16% 7% 6% 5% 4 6% 7% 26%	6974
February	1st to 10th	Night	9% 11% 5% 11% 8% 7% 6% 5% 6% 8% 25%	2800
	11th to 20th	Night	5% 10% 4 10% 7% 7% 6% 6% 8% 6% 32%	2534
	21st to end	Night	6% 11% 4 10% 7% 6% 5% 4 6% 8% 33%	1938
March	1st to 10th	Night	8% 12% 5% 10% 7% 5% 5% 4 6% 7% 32%	3734
	11th to 20th	Night	7% 9% 3 8% 5% 5% 4 3 5% 8% 40%	3675
	21st to end	Night	7% 9% 5% 13% 7% 6% 5% 4 5% 6% 34%	3553
April	1st to 10th	Night	4 10% 3 8% 4 4 4 4 6% 8% 45%	1900
	11th to 20th	Night	14% 13% 4 9% 5% 4 4 4 6% 7% 31%	1746
	21st to end	Night	14% 8% 3 7% 5% 5% 5% 4 6% 7% 37%	1710
May	1st to 10th	Night	17% 9% 2 7% 4 5% 5% 4 6% 7% 35%	2541
	11th to 20th	Night	11% 8% 3 8% 6% 4 6% 4 6% 6% 39%	2435
	21st to end	Night	15% 7% 3 6% 4 4 5% 4 6% 7% 40%	2414
June	1st to 10th	Night	14% 5% 2 5% 5% 4 4 3 7% 6% 45%	1330
	11th to 20th	Night	15% 5% 2 5% 4 4 5% 4 5% 9% 41%	1330
	21st to end	Night	12% 5% 2 5% 4 5% 5% 4 7% 7% 44%	1330
July	1st to 10th	Night	7% 3 2 4 4 5% 5% 4 7% 10% 48%	2220
	11th to 20th	Night	5% 3 1 4 3 3 4 4 5% 8% 60%	2343
	21st to end	Night	4 3 1 4 3 3 4 4 7% 10% 59%	2762
August	1st to 10th	Night	7% 5% 2 5% 4 4 5% 4 7% 8% 52%	2528
	11th to 20th	Night	4 4 2 6% 5% 4 5% 4 6% 9% 53%	2619
	21st to end	Night	8% 4 1 5% 3 3 4 3 7% 8% 53%	3231
September	1st to 10th	Night	9% 4 2 6% 4 3 4 3 6% 6% 54%	1900
	11th to 20th	Night	12% 6% 2 5% 4 4 4 3 6% 8% 46%	2019
	21st to end	Night	13% 7% 2 5% 4 3 4 4 6% 7% 44%	2090
October	1st to 10th	Night	11% 9% 2 5% 3 3 4 3 4 6% 49%	3596
	11th to 20th	Night	7% 6% 2 6% 3 4 5% 5% 8% 9% 43%	4060
	21st to end	Night	8% 9% 4 8% 4 4 4 4 5% 7% 43%	4467
November	1st to 10th	Night	13% 14% 5% 10% 5% 4 4 3 5% 6% 31%	2535
	11th to 20th	Night	9% 13% 6% 13% 9% 5% 5% 3 5% 6% 28%	2908
	21st to end	Night	9% 12% 5% 10% 7% 6% 5% 4 5% 8% 29%	3000
December	1st to 10th	Night	7% 12% 5% 14% 10% 9% 8% 6% 5% 6% 18%	4900
	11th to 20th	Night	8% 14% 4 13% 9% 7% 7% 5% 6% 6% 22%	5568
	21st to end	Night	5% 7% 3 13% 8% 6% 6% 4 6% 6% 35%	7480

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	64% 6% 11% 13% 6%	3243
	11th to 20th	Day	57% 6% 13% 16% 7%	3640
	21st to end	Day	54% 7% 15% 20% 4	4004
February	1st to 10th	Day	59% 4 12% 16% 8% 1	1600
	11th to 20th	Day	53% 5% 11% 21% 10%	1780
	21st to end	Day	54% 6% 12% 18% 10%	1610
March	1st to 10th	Day	57% 7% 13% 18% 4	3130
	11th to 20th	Day	54% 8% 15% 18% 5%	3290
	21st to end	Day	51% 7% 13% 17% 11%	4083
April	1st to 10th	Day	43% 7% 15% 24% 11%	2280
	11th to 20th	Day	54% 5% 12% 19% 9% 1	2385
	21st to end	Day	45% 6% 16% 24% 8%	2470
May	1st to 10th	Day	47% 5% 14% 24% 8% 1	4425
	11th to 20th	Day	48% 7% 10% 22% 11% 1	4473
	21st to end	Day	43% 8% 13% 28% 7%	5173
June	1st to 10th	Day	40% 8% 17% 24% 9% 2	2850
	11th to 20th	Day	46% 8% 16% 20% 9% 1	2850
	21st to end	Day	40% 9% 17% 27% 7% 1	2850
July	1st to 10th	Day	33% 9% 25% 28% 5%	4676
	11th to 20th	Day	27% 7% 18% 38% 9%	4542
	21st to end	Day	24% 8% 22% 33% 11% 2	4651
August	1st to 10th	Day	34% 7% 17% 31% 11% 1	4396
	11th to 20th	Day	29% 7% 21% 37% 7%	4262
	21st to end	Day	32% 7% 17% 36% 8%	4418
September	1st to 10th	Day	32% 6% 15% 33% 13% 1	2280
	11th to 20th	Day	40% 7% 15% 27% 10% 1	2161
	21st to end	Day	38% 4 13% 31% 14%	2090
October	1st to 10th	Day	40% 5% 15% 32% 8%	3366
	11th to 20th	Day	33% 4 18% 35% 10%	2837
	21st to end	Day	48% 4 12% 28% 8%	3091
November	1st to 10th	Day	58% 5% 12% 17% 7% 1	1763
	11th to 20th	Day	58% 5% 15% 14% 7% 1	1487
	21st to end	Day	56% 7% 13% 17% 6%	1400
December	1st to 10th	Day	65% 7% 13% 11% 3	2290
	11th to 20th	Day	64% 6% 13% 14% 3	2640
	21st to end	Day	46% 5% 6% 26% 14% 2	3498
January	1st to 10th	Night	63% 5% 10% 17% 5%	6718
	11th to 20th	Night	56% 8% 14% 15% 6%	6340
	21st to end	Night	56% 7% 16% 17% 4	6974
February	1st to 10th	Night	54% 6% 12% 18% 9% 1	2800
	11th to 20th	Night	47% 5% 13% 21% 13% 1	2536
	21st to end	Night	46% 7% 12% 23% 13%	1938
March	1st to 10th	Night	50% 6% 15% 22% 7%	3734
	11th to 20th	Night	39% 6% 18% 27% 9% 1	3675
	21st to end	Night	49% 6% 12% 21% 11% 1	3553
April	1st to 10th	Night	36% 6% 12% 26% 18% 1	1900
	11th to 20th	Night	52% 5% 10% 21% 12% 1	1746
	21st to end	Night	45% 5% 14% 23% 12% 1	1710
May	1st to 10th	Night	46% 7% 12% 20% 15%	2541
	11th to 20th	Night	42% 8% 12% 22% 12% 3	2435
	21st to end	Night	40% 7% 15% 28% 10%	2414
June	1st to 10th	Night	38% 7% 16% 24% 13% 2	1330
	11th to 20th	Night	39% 7% 18% 21% 13% 2	1330
	21st to end	Night	37% 7% 18% 29% 7% 1	1330
July	1st to 10th	Night	29% 11% 26% 25% 8%	2185
	11th to 20th	Night	22% 7% 19% 44% 8% 1	2301
	21st to end	Night	20% 7% 22% 31% 17% 3	2674
August	1st to 10th	Night	28% 7% 20% 31% 13% 1	2520
	11th to 20th	Night	27% 6% 20% 37% 8% 1	2643
	21st to end	Night	28% 7% 18% 36% 11% 1	3231
September	1st to 10th	Night	29% 5% 12% 34% 17% 2	1900
	11th to 20th	Night	35% 8% 15% 29% 13% 1	2019
	21st to end	Night	39% 5% 11% 30% 12% 2	2090
October	1st to 10th	Night	36% 4 13% 32% 10% 4	3596
	11th to 20th	Night	35% 5% 13% 34% 11% 2	4060
	21st to end	Night	41% 4 13% 32% 10%	4467
November	1st to 10th	Night	53% 5% 13% 19% 7% 2	2535
	11th to 20th	Night	57% 6% 13% 18% 5% 1	2908
	21st to end	Night	52% 8% 16% 18% 6%	3000
December	1st to 10th	Night	65% 6% 13% 12% 4	4900
	11th to 20th	Night	61% 6% 12% 17% 4 1	5566
	21st to end	Night	48% 5% 9% 21% 14% 3	7480

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% 11% 32% 31% 12% 3	300
	11th to 20th	Day	8% 11% 40% 31% 9% 1	300
	21st to end	Day	16% 11% 33% 29% 10% 1	330
February	1st to 10th	Day	14% 12% 38% 27% 8%	300
	11th to 20th	Day	10% 9% 37% 30% 11% 2	300
	21st to end	Day	8% 6% 34% 32% 16% 3	237
March	1st to 10th	Day	16% 9% 34% 27% 12% 2	270
	11th to 20th	Day	14% 12% 30% 30% 13% 2	270
	21st to end	Day	16% 7% 35% 26% 14% 2	450
April	1st to 10th	Day	13% 15% 37% 28% 6% 1	460
	11th to 20th	Day	22% 12% 30% 26% 9% 1	583
	21st to end	Day	16% 9% 32% 27% 14% 1	650
May	1st to 10th	Day	15% 10% 29% 29% 15% 2	653
	11th to 20th	Day	17% 10% 28% 24% 15% 5%	675
	21st to end	Day	19% 8% 26% 27% 15% 4	734
June	1st to 10th	Day	15% 12% 29% 26% 14% 4	680
	11th to 20th	Day	19% 9% 32% 25% 11% 3	680
	21st to end	Day	12% 10% 27% 31% 16% 3	680
July	1st to 10th	Day	10% 7% 25% 34% 18% 6%	671
	11th to 20th	Day	9% 11% 30% 28% 18% 6%	668
	21st to end	Day	5% 7% 28% 37% 16% 7%	739
August	1st to 10th	Day	12% 6% 26% 34% 17% 6%	676
	11th to 20th	Day	11% 7% 25% 28% 23% 6%	665
	21st to end	Day	14% 6% 26% 32% 18% 4	687
September	1st to 10th	Day	13% 10% 36% 26% 12% 3	490
	11th to 20th	Day	17% 12% 28% 30% 11% 1	371
	21st to end	Day	20% 11% 31% 27% 11% 1	300
October	1st to 10th	Day	20% 12% 27% 25% 13% 2	300
	11th to 20th	Day	16% 12% 37% 24% 7% 4	300
	21st to end	Day	19% 11% 38% 24% 5% 2	330
November	1st to 10th	Day	26% 11% 32% 18% 11% 3	300
	11th to 20th	Day	18% 14% 38% 23% 6% 1	300
	21st to end	Day	15% 16% 38% 23% 6% 1	300
December	1st to 10th	Day	12% 12% 39% 24% 11% 3	300
	11th to 20th	Day	16% 11% 46% 20% 6% 1	300
	21st to end	Day	8% 9% 40% 25% 14% 5%	330
January	1st to 10th	Night	10% 12% 38% 31% 8% 1	1000
	11th to 20th	Night	13% 13% 37% 29% 8% 1	1000
	21st to end	Night	11% 13% 41% 27% 7% 1	1100
February	1st to 10th	Night	14% 10% 37% 27% 11% 2	1000
	11th to 20th	Night	10% 9% 38% 30% 9% 3	881
	21st to end	Night	9% 8% 31% 36% 14% 3	646
March	1st to 10th	Night	15% 9% 31% 32% 11% 2	760
	11th to 20th	Night	10% 7% 39% 29% 13% 2	687
	21st to end	Night	15% 6% 32% 32% 13% 3	627
April	1st to 10th	Night	7% 10% 35% 37% 11% 1	570
	11th to 20th	Night	20% 9% 32% 31% 7% 1	563
	21st to end	Night	18% 6% 34% 32% 9% 1	570
May	1st to 10th	Night	16% 7% 26% 37% 12% 1	570
	11th to 20th	Night	14% 6% 29% 36% 15%	561
	21st to end	Night	23% 5% 25% 33% 13% 1	617
June	1st to 10th	Night	16% 5% 31% 33% 14% 1	570
	11th to 20th	Night	18% 4 34% 30% 13% 1	570
	21st to end	Night	15% 5% 27% 37% 16% 1	570
July	1st to 10th	Night	8% 4 25% 42% 20% 1	555
	11th to 20th	Night	7% 5% 32% 39% 16% 1	552
	21st to end	Night	5% 5% 28% 42% 18% 3	624
August	1st to 10th	Night	6% 5% 24% 46% 19% 1	567
	11th to 20th	Night	6% 4 24% 39% 25% 2	564
	21st to end	Night	11% 5% 27% 41% 16% 1	627
September	1st to 10th	Night	12% 5% 28% 36% 16% 4	570
	11th to 20th	Night	13% 7% 32% 34% 13% 1	570
	21st to end	Night	15% 8% 30% 35% 11% 1	570
October	1st to 10th	Night	19% 10% 28% 31% 12% 1	634
	11th to 20th	Night	16% 11% 32% 29% 12% 1	926
	21st to end	Night	16% 12% 36% 28% 7% 1	1045
November	1st to 10th	Night	18% 12% 35% 25% 8% 1	975
	11th to 20th	Night	14% 11% 41% 26% 7% 1	1000
	21st to end	Night	15% 15% 36% 29% 6% 1	1000
December	1st to 10th	Night	12% 11% 36% 28% 10% 3	1000
	11th to 20th	Night	15% 14% 34% 27% 10% 1	1000
	21st to end	Night	13% 8% 35% 31% 10% 2	1100

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