Assiniboia
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Assiniboia clear sky chart from 2005-11-06 to 2024-03-01.

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% 4 7% 6% 4 5% 5% 6% 7% 40%	77973
	Night	8% 8% 4 7% 6% 4 5% 5% 6% 7% 40%	81431
Transparency	Day	42% 6% 16% 24% 11% 1	77664
	Night	42% 6% 15% 24% 11% 2	81261
Seeing	Day	13% 9% 30% 29% 16% 4	14877
	Night	12% 8% 33% 34% 12% 1	24581

By Month

Percentage Cloud Cover SW (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	6% 11% 5% 9% 9% 5% 8% 6% 5% 6% 30%	2219
	11th to 20th	Day	4 6% 5% 8% 11% 6% 12% 11% 8% 7% 22%	2420
	21st to end	Day	4 10% 4 9% 7% 3 6% 5% 5% 7% 39%	2794
February	1st to 10th	Day	9% 11% 8% 12% 9% 5% 7% 4 6% 6% 24%	1647
	11th to 20th	Day	7% 12% 5% 10% 8% 5% 8% 6% 6% 7% 26%	1665
	21st to end	Day	5% 9% 6% 11% 8% 4 7% 7% 6% 8% 29%	1498
March	1st to 10th	Day	7% 13% 7% 11% 10% 5% 6% 6% 7% 8% 22%	1800
	11th to 20th	Day	9% 10% 5% 7% 5% 4 5% 5% 7% 9% 34%	1944
	21st to end	Day	9% 12% 5% 9% 7% 4 6% 5% 7% 9% 28%	2301
April	1st to 10th	Day	10% 8% 4 6% 6% 4 6% 5% 6% 8% 37%	2160
	11th to 20th	Day	13% 13% 5% 8% 6% 4 5% 6% 6% 7% 27%	2135
	21st to end	Day	17% 9% 3 6% 5% 4 5% 5% 4 7% 37%	2479
May	1st to 10th	Day	14% 8% 3 6% 5% 3 5% 6% 5% 7% 38%	2520
	11th to 20th	Day	10% 7% 3 6% 6% 4 5% 6% 6% 8% 40%	2478
	21st to end	Day	20% 6% 3 6% 6% 3 5% 4 6% 6% 33%	2724
June	1st to 10th	Day	16% 6% 2 5% 6% 3 4 6% 6% 7% 39%	2636
	11th to 20th	Day	17% 7% 3 6% 6% 4 5% 5% 6% 7% 34%	2700
	21st to end	Day	9% 4 2 4 5% 3 5% 6% 7% 9% 45%	2700
July	1st to 10th	Day	6% 3 2 4 4 4 6% 6% 6% 9% 52%	2700
	11th to 20th	Day	6% 3 1 5% 4 2 4 4 6% 9% 56%	2645
	21st to end	Day	6% 2 2 4 4 2 4 5% 5% 7% 60%	2742
August	1st to 10th	Day	8% 4 2 4 5% 3 5% 4 5% 8% 53%	2507
	11th to 20th	Day	9% 4 2 3 4 3 4 4 6% 8% 54%	2394
	21st to end	Day	10% 4 2 4 4 3 3 3 5% 8% 55%	2453
September	1st to 10th	Day	11% 6% 2 4 5% 2 4 4 5% 7% 49%	2160
	11th to 20th	Day	13% 7% 3 5% 4 2 4 4 4 7% 48%	2160
	21st to end	Day	14% 5% 2 4 4 3 4 4 5% 8% 47%	1927
October	1st to 10th	Day	16% 8% 2 5% 4 3 3 4 5% 6% 45%	1800
	11th to 20th	Day	10% 7% 4 6% 6% 3 4 4 5% 6% 43%	1784
	21st to end	Day	9% 10% 4 9% 5% 3 4 4 6% 8% 37%	1782
November	1st to 10th	Day	12% 12% 5% 8% 7% 3 4 4 5% 7% 34%	1531
	11th to 20th	Day	5% 10% 5% 11% 8% 4 5% 4 6% 6% 36%	1520
	21st to end	Day	9% 10% 6% 7% 6% 5% 6% 5% 6% 6% 34%	1520
December	1st to 10th	Day	8% 11% 6% 11% 11% 6% 6% 5% 5% 6% 24%	1427
	11th to 20th	Day	5% 11% 6% 12% 7% 4 6% 6% 6% 8% 30%	1659
	21st to end	Day	6% 8% 3 6% 6% 3 5% 4 5% 7% 47%	2442
January	1st to 10th	Night	3 9% 5% 11% 7% 5% 6% 7% 7% 7% 33%	4726
	11th to 20th	Night	3 6% 4 11% 12% 7% 9% 8% 8% 6% 26%	4543
	21st to end	Night	4 12% 5% 8% 6% 3 5% 5% 6% 7% 39%	4873
February	1st to 10th	Night	7% 11% 6% 9% 9% 5% 6% 6% 6% 6% 28%	2551
	11th to 20th	Night	6% 12% 5% 10% 8% 5% 5% 5% 6% 7% 31%	2402
	21st to end	Night	6% 9% 5% 9% 7% 4 6% 5% 5% 7% 36%	1956
March	1st to 10th	Night	6% 10% 5% 10% 9% 5% 6% 6% 5% 9% 30%	2166
	11th to 20th	Night	7% 11% 4 7% 6% 4 6% 5% 5% 7% 38%	2014
	21st to end	Night	9% 10% 5% 9% 7% 4 5% 5% 6% 8% 33%	2054
April	1st to 10th	Night	7% 9% 3 7% 6% 4 4 5% 6% 9% 40%	1800
	11th to 20th	Night	13% 12% 5% 8% 5% 3 5% 5% 6% 8% 32%	1771
	21st to end	Night	12% 8% 3 7% 6% 2 5% 7% 7% 8% 35%	1481
May	1st to 10th	Night	12% 6% 3 6% 4 3 4 4 7% 10% 42%	1440
	11th to 20th	Night	11% 6% 2 5% 6% 3 6% 4 6% 9% 43%	1417
	21st to end	Night	18% 5% 3 5% 5% 4 5% 6% 7% 11% 33%	1552
June	1st to 10th	Night	13% 5% 2 5% 4 2 5% 5% 6% 8% 46%	1320
	11th to 20th	Night	12% 6% 2 4 4 3 5% 7% 5% 10% 42%	1260
	21st to end	Night	8% 4 2 5% 4 3 4 5% 5% 9% 52%	1260
July	1st to 10th	Night	6% 3 1 4 3 2 4 4 6% 8% 57%	1260
	11th to 20th	Night	6% 4 1 3 3 2 4 4 7% 8% 58%	1314
	21st to end	Night	3 2 1 3 3 2 4 4 6% 8% 64%	1576
August	1st to 10th	Night	7% 3 1 4 3 2 2 4 7% 8% 58%	1432
	11th to 20th	Night	6% 3 1 3 3 2 3 3 6% 9% 61%	1504
	21st to end	Night	8% 3 1 3 4 2 3 4 5% 6% 61%	1903
September	1st to 10th	Night	9% 5% 1 4 5% 3 4 4 5% 7% 54%	1800
	11th to 20th	Night	10% 5% 2 4 4 3 3 4 5% 9% 51%	1800
	21st to end	Night	11% 4 2 4 4 3 4 4 5% 7% 53%	2032
October	1st to 10th	Night	14% 7% 2 5% 3 2 4 3 5% 7% 48%	2160
	11th to 20th	Night	9% 7% 4 7% 4 3 4 4 5% 7% 47%	2160
	21st to end	Night	9% 10% 4 8% 6% 3 4 5% 6% 8% 36%	2571
November	1st to 10th	Night	13% 13% 4 7% 6% 3 4 4 5% 6% 35%	2544
	11th to 20th	Night	7% 10% 4 10% 8% 4 5% 5% 6% 7% 35%	2660
	21st to end	Night	7% 11% 5% 9% 6% 4 5% 5% 4 8% 36%	2660
December	1st to 10th	Night	7% 11% 5% 11% 10% 4 7% 5% 4 6% 29%	2744
	11th to 20th	Night	6% 11% 6% 10% 9% 5% 6% 6% 6% 7% 29%	3511
	21st to end	Night	4 7% 3 6% 6% 3 4 4 4 6% 53%	5214

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	54% 7% 16% 19% 4	2219
	11th to 20th	Day	55% 9% 14% 17% 5%	2420
	21st to end	Day	43% 6% 19% 27% 5%	2794
February	1st to 10th	Day	59% 5% 10% 17% 9%	1647
	11th to 20th	Day	55% 6% 13% 13% 12% 1	1674
	21st to end	Day	51% 7% 16% 16% 9%	1498
March	1st to 10th	Day	58% 8% 14% 16% 4	1800
	11th to 20th	Day	46% 6% 18% 22% 7% 1	1944
	21st to end	Day	51% 8% 20% 15% 6%	2301
April	1st to 10th	Day	44% 7% 15% 21% 12% 1	2160
	11th to 20th	Day	54% 6% 15% 18% 6% 1	2138
	21st to end	Day	47% 6% 16% 23% 8% 1	2479
May	1st to 10th	Day	45% 4 13% 26% 11% 1	2520
	11th to 20th	Day	40% 7% 13% 30% 10%	2482
	21st to end	Day	50% 6% 13% 21% 8% 1	2724
June	1st to 10th	Day	42% 7% 18% 24% 8% 1	2636
	11th to 20th	Day	47% 7% 15% 20% 10% 1	2700
	21st to end	Day	33% 7% 19% 31% 9% 1	2700
July	1st to 10th	Day	26% 7% 19% 33% 13% 2	2626
	11th to 20th	Day	24% 8% 17% 28% 20% 3	2564
	21st to end	Day	23% 5% 12% 35% 22% 3	2590
August	1st to 10th	Day	30% 6% 15% 31% 15% 3	2491
	11th to 20th	Day	28% 5% 19% 29% 16% 2	2394
	21st to end	Day	28% 5% 12% 34% 19% 3	2453
September	1st to 10th	Day	34% 5% 14% 27% 16% 3	2160
	11th to 20th	Day	36% 5% 16% 28% 13% 3	2160
	21st to end	Day	37% 5% 13% 29% 15% 2	1927
October	1st to 10th	Day	42% 4 16% 26% 12% 1	1800
	11th to 20th	Day	41% 5% 14% 28% 11% 1	1784
	21st to end	Day	45% 6% 19% 23% 8%	1782
November	1st to 10th	Day	50% 6% 14% 20% 9% 1	1531
	11th to 20th	Day	49% 6% 16% 21% 8% 1	1520
	21st to end	Day	49% 7% 21% 17% 5% 1	1520
December	1st to 10th	Day	59% 6% 15% 14% 5%	1427
	11th to 20th	Day	51% 7% 24% 12% 6%	1657
	21st to end	Day	37% 5% 12% 24% 15% 7%	2442
January	1st to 10th	Night	46% 7% 20% 20% 6% 1	4726
	11th to 20th	Night	53% 6% 16% 19% 5% 1	4543
	21st to end	Night	44% 6% 21% 24% 5%	4873
February	1st to 10th	Night	54% 6% 14% 18% 8% 1	2551
	11th to 20th	Night	51% 5% 15% 17% 10% 1	2403
	21st to end	Night	46% 5% 13% 24% 11%	1956
March	1st to 10th	Night	51% 6% 16% 21% 7%	2166
	11th to 20th	Night	46% 6% 13% 25% 9% 1	2014
	21st to end	Night	49% 5% 17% 20% 8%	2054
April	1st to 10th	Night	40% 6% 14% 25% 13% 1	1800
	11th to 20th	Night	49% 6% 13% 19% 12% 2	1771
	21st to end	Night	45% 6% 14% 25% 10%	1481
May	1st to 10th	Night	37% 5% 13% 28% 15% 1	1440
	11th to 20th	Night	38% 5% 14% 27% 15% 1	1418
	21st to end	Night	44% 9% 15% 22% 10% 1	1552
June	1st to 10th	Night	35% 6% 17% 28% 13% 1	1320
	11th to 20th	Night	36% 7% 19% 23% 14% 1	1260
	21st to end	Night	29% 8% 17% 34% 11% 1	1260
July	1st to 10th	Night	23% 7% 17% 36% 15% 3	1225
	11th to 20th	Night	23% 6% 18% 30% 20% 3	1272
	21st to end	Night	17% 5% 13% 36% 25% 4	1488
August	1st to 10th	Night	23% 4 16% 35% 19% 2	1424
	11th to 20th	Night	21% 5% 16% 36% 20% 2	1504
	21st to end	Night	24% 4 12% 28% 28% 5%	1903
September	1st to 10th	Night	31% 4 11% 29% 20% 5%	1800
	11th to 20th	Night	31% 5% 14% 27% 19% 4	1800
	21st to end	Night	32% 4 12% 32% 18% 2	2032
October	1st to 10th	Night	37% 5% 16% 26% 15% 1	2160
	11th to 20th	Night	37% 4 14% 30% 13% 1	2160
	21st to end	Night	45% 6% 14% 24% 9% 2	2571
November	1st to 10th	Night	50% 5% 14% 20% 9% 2	2544
	11th to 20th	Night	49% 5% 19% 20% 7% 1	2660
	21st to end	Night	48% 5% 20% 20% 7%	2660
December	1st to 10th	Night	56% 5% 14% 17% 7% 1	2744
	11th to 20th	Night	54% 7% 15% 19% 5% 1	3512
	21st to end	Night	33% 4 12% 28% 16% 6%	5214

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	9% 14% 32% 25% 15% 4	180
	11th to 20th	Day	11% 10% 33% 27% 14% 4	238
	21st to end	Day	13% 12% 33% 30% 10% 2	297
February	1st to 10th	Day	17% 9% 41% 26% 7% 1	270
	11th to 20th	Day	10% 10% 40% 25% 12% 2	270
	21st to end	Day	6% 8% 35% 34% 14% 3	225
March	1st to 10th	Day	14% 7% 37% 29% 11% 2	240
	11th to 20th	Day	12% 12% 34% 24% 13% 5%	384
	21st to end	Day	14% 9% 36% 23% 13% 5%	462
April	1st to 10th	Day	11% 15% 40% 28% 6%	420
	11th to 20th	Day	19% 13% 33% 26% 7% 2	412
	21st to end	Day	20% 10% 28% 30% 12% 1	559
May	1st to 10th	Day	15% 6% 24% 31% 19% 5%	603
	11th to 20th	Day	14% 8% 24% 29% 19% 7%	625
	21st to end	Day	17% 9% 24% 25% 20% 7%	679
June	1st to 10th	Day	15% 11% 26% 27% 16% 5%	630
	11th to 20th	Day	17% 13% 31% 24% 12% 3	630
	21st to end	Day	10% 5% 26% 31% 21% 6%	630
July	1st to 10th	Day	6% 4 27% 34% 23% 5%	621
	11th to 20th	Day	6% 6% 27% 39% 17% 4	618
	21st to end	Day	6% 5% 26% 32% 26% 5%	684
August	1st to 10th	Day	10% 4 21% 37% 22% 6%	626
	11th to 20th	Day	11% 5% 23% 31% 23% 8%	532
	21st to end	Day	12% 5% 21% 36% 20% 7%	495
September	1st to 10th	Day	12% 8% 31% 30% 15% 4	450
	11th to 20th	Day	15% 8% 25% 34% 16% 3	450
	21st to end	Day	18% 9% 26% 31% 13% 4	298
October	1st to 10th	Day	23% 6% 24% 24% 21% 3	270
	11th to 20th	Day	10% 13% 34% 26% 12% 5%	270
	21st to end	Day	16% 11% 39% 23% 8% 2	297
November	1st to 10th	Day	21% 10% 35% 21% 11% 2	270
	11th to 20th	Day	12% 16% 34% 25% 12% 1	270
	21st to end	Day	11% 12% 37% 26% 13% 1	270
December	1st to 10th	Day	12% 9% 44% 23% 8% 3	270
	11th to 20th	Day	10% 15% 44% 21% 9% 1	234
	21st to end	Day	13% 6% 36% 30% 12% 3	198
January	1st to 10th	Night	7% 14% 39% 29% 10% 1	950
	11th to 20th	Night	10% 13% 39% 29% 8% 1	950
	21st to end	Night	12% 10% 39% 28% 9% 1	1045
February	1st to 10th	Night	11% 10% 33% 31% 13% 2	841
	11th to 20th	Night	12% 10% 40% 29% 9% 1	744
	21st to end	Night	8% 8% 31% 32% 17% 4	628
March	1st to 10th	Night	10% 9% 35% 33% 11% 2	722
	11th to 20th	Night	11% 9% 34% 32% 11% 2	720
	21st to end	Night	14% 7% 28% 37% 14% 1	668
April	1st to 10th	Night	10% 10% 31% 38% 10%	540
	11th to 20th	Night	16% 7% 36% 32% 8%	533
	21st to end	Night	17% 8% 31% 36% 8%	540
May	1st to 10th	Night	14% 5% 27% 37% 15% 1	540
	11th to 20th	Night	15% 6% 24% 35% 17% 2	531
	21st to end	Night	19% 7% 23% 31% 19% 1	584
June	1st to 10th	Night	13% 7% 28% 36% 14% 2	420
	11th to 20th	Night	16% 6% 26% 38% 14%	360
	21st to end	Night	13% 4 25% 40% 17% 2	360
July	1st to 10th	Night	8% 3 24% 46% 18% 1	350
	11th to 20th	Night	8% 3 29% 45% 14% 1	402
	21st to end	Night	3 3 29% 48% 16% 1	591
August	1st to 10th	Night	8% 3 23% 47% 17% 3	537
	11th to 20th	Night	6% 4 21% 44% 23% 2	534
	21st to end	Night	10% 3 23% 42% 20% 1	594
September	1st to 10th	Night	10% 4 25% 44% 15% 2	540
	11th to 20th	Night	10% 5% 24% 45% 16% 1	540
	21st to end	Night	12% 5% 29% 40% 12% 1	620
October	1st to 10th	Night	18% 7% 27% 34% 14% 1	720
	11th to 20th	Night	13% 6% 33% 33% 13% 2	720
	21st to end	Night	15% 10% 38% 30% 8%	987
November	1st to 10th	Night	21% 10% 35% 29% 6% 1	925
	11th to 20th	Night	12% 11% 41% 26% 9% 1	950
	21st to end	Night	12% 10% 46% 24% 7% 1	950
December	1st to 10th	Night	13% 8% 39% 27% 11% 2	950
	11th to 20th	Night	13% 12% 36% 28% 9% 1	950
	21st to end	Night	12% 8% 37% 31% 10% 2	1045

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