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 2024-11-01.

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	9% 8% 3 8% 5% 5% 5% 4 6% 7% 41%	101557
	Night	7% 8% 3 8% 5% 5% 5% 4 6% 7% 41%	97523
Transparency	Day	41% 6% 16% 25% 11% 1	101291
	Night	41% 6% 16% 25% 11% 2	97378
Seeing	Day	13% 9% 30% 29% 16% 4	15920
	Night	12% 8% 33% 34% 12% 1	25344

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% 4 11% 7% 8% 7% 5% 5% 6% 30%	2219
	11th to 20th	Day	4 7% 4 10% 9% 9% 12% 8% 8% 7% 22%	2420
	21st to end	Day	4 11% 4 10% 6% 4 6% 4 5% 7% 39%	2794
February	1st to 10th	Day	9% 14% 6% 12% 8% 6% 7% 3 6% 6% 24%	1647
	11th to 20th	Day	7% 13% 4 10% 7% 8% 7% 5% 6% 6% 25%	1665
	21st to end	Day	4 12% 4 12% 7% 5% 6% 6% 6% 7% 29%	1498
March	1st to 10th	Day	5% 13% 7% 14% 8% 6% 3 3 5% 6% 29%	3130
	11th to 20th	Day	6% 12% 5% 10% 4 4 4 3 6% 9% 36%	3426
	21st to end	Day	8% 16% 5% 13% 5% 6% 5% 4 6% 7% 24%	4038
April	1st to 10th	Day	9% 10% 3 8% 5% 5% 6% 4 6% 8% 36%	2280
	11th to 20th	Day	12% 14% 5% 9% 6% 5% 5% 5% 6% 7% 27%	2256
	21st to end	Day	17% 9% 3 7% 4 4 5% 4 4 7% 37%	2617
May	1st to 10th	Day	19% 12% 4 7% 4 4 4 4 5% 6% 32%	4430
	11th to 20th	Day	9% 7% 3 8% 5% 5% 6% 5% 7% 9% 36%	4388
	21st to end	Day	15% 7% 3 8% 5% 5% 5% 4 6% 7% 34%	4825
June	1st to 10th	Day	16% 6% 2 5% 5% 4 4 5% 6% 7% 39%	2783
	11th to 20th	Day	17% 7% 2 7% 5% 5% 5% 4 6% 7% 34%	2850
	21st to end	Day	9% 5% 2 5% 5% 5% 5% 5% 7% 9% 45%	2850
July	1st to 10th	Day	4 4 2 6% 5% 6% 6% 5% 8% 9% 46%	4740
	11th to 20th	Day	4 2 1 4 3 3 4 4 7% 9% 59%	4633
	21st to end	Day	4 2 1 4 3 3 4 4 5% 7% 64%	4802
August	1st to 10th	Day	8% 4 2 5% 4 5% 4 4 5% 6% 54%	4411
	11th to 20th	Day	6% 3 1 4 4 4 4 4 6% 9% 55%	4190
	21st to end	Day	9% 4 2 4 3 3 3 2 5% 7% 58%	4309
September	1st to 10th	Day	11% 5% 2 5% 4 3 3 4 5% 7% 50%	2280
	11th to 20th	Day	12% 7% 2 6% 4 3 4 3 5% 7% 46%	2280
	21st to end	Day	13% 5% 2 5% 3 4 3 3 6% 7% 48%	2033
October	1st to 10th	Day	15% 8% 2 6% 3 4 3 3 5% 6% 45%	1900
	11th to 20th	Day	9% 8% 4 7% 5% 4 4 3 5% 7% 44%	1883
	21st to end	Day	9% 11% 4 9% 4 5% 4 4 6% 8% 38%	1881
November	1st to 10th	Day	12% 13% 4 9% 6% 4 3 4 5% 7% 34%	1531
	11th to 20th	Day	5% 11% 5% 12% 6% 5% 4 4 6% 6% 35%	1520
	21st to end	Day	9% 11% 5% 8% 6% 7% 5% 4 6% 6% 33%	1520
December	1st to 10th	Day	7% 12% 5% 13% 10% 7% 5% 5% 6% 5% 24%	1427
	11th to 20th	Day	5% 12% 5% 13% 5% 5% 6% 4 6% 8% 29%	1659
	21st to end	Day	6% 8% 3 7% 5% 4 5% 3 5% 6% 47%	2442
January	1st to 10th	Night	3 10% 4 12% 6% 6% 6% 5% 7% 7% 33%	4726
	11th to 20th	Night	3 7% 4 12% 10% 9% 9% 6% 8% 6% 26%	4543
	21st to end	Night	4 12% 4 9% 5% 4 5% 4 6% 7% 39%	4873
February	1st to 10th	Night	7% 13% 5% 10% 8% 7% 6% 5% 6% 6% 27%	2551
	11th to 20th	Night	6% 13% 4 11% 7% 5% 5% 4 7% 7% 31%	2402
	21st to end	Night	5% 10% 5% 10% 7% 6% 6% 4 6% 7% 35%	1956
March	1st to 10th	Night	5% 9% 4 13% 9% 7% 5% 4 6% 9% 30%	3734
	11th to 20th	Night	4 9% 4 9% 5% 5% 4 4 5% 8% 41%	3537
	21st to end	Night	9% 13% 6% 14% 7% 5% 5% 4 5% 6% 25%	3607
April	1st to 10th	Night	6% 9% 3 8% 5% 4 4 4 7% 9% 40%	1900
	11th to 20th	Night	12% 12% 4 9% 4 4 5% 4 6% 8% 32%	1870
	21st to end	Night	11% 8% 2 8% 5% 4 5% 5% 7% 7% 37%	1563
May	1st to 10th	Night	20% 10% 3 7% 4 4 3 4 6% 7% 33%	2540
	11th to 20th	Night	11% 6% 2 6% 4 5% 5% 4 7% 10% 41%	2517
	21st to end	Night	15% 6% 2 6% 5% 5% 5% 5% 7% 9% 37%	2762
June	1st to 10th	Night	12% 6% 2 5% 3 3 5% 4 6% 8% 46%	1393
	11th to 20th	Night	12% 6% 2 5% 4 3 5% 5% 6% 10% 43%	1330
	21st to end	Night	8% 4 2 5% 3 4 5% 3 6% 8% 52%	1330
July	1st to 10th	Night	5% 3 2 4 3 4 5% 5% 7% 10% 53%	2220
	11th to 20th	Night	4 3 1 4 3 4 4 4 6% 8% 58%	2316
	21st to end	Night	2 3 1 3 3 3 4 3 7% 8% 64%	2761
August	1st to 10th	Night	8% 5% 1 4 3 2 3 3 6% 7% 58%	2528
	11th to 20th	Night	5% 2 2 4 3 3 4 3 7% 9% 58%	2646
	21st to end	Night	7% 3 1 3 4 3 4 4 5% 7% 57%	3358
September	1st to 10th	Night	9% 4 1 4 4 3 4 3 4 7% 56%	1900
	11th to 20th	Night	10% 5% 2 5% 4 4 3 3 5% 8% 50%	1900
	21st to end	Night	11% 4 1 5% 3 3 4 3 5% 7% 53%	2146
October	1st to 10th	Night	13% 7% 2 5% 3 3 3 3 5% 7% 48%	2280
	11th to 20th	Night	8% 8% 3 7% 4 4 4 3 6% 7% 48%	2280
	21st to end	Night	9% 11% 3 9% 5% 4 5% 4 6% 8% 37%	2714
November	1st to 10th	Night	13% 14% 4 8% 5% 4 4 3 5% 5% 35%	2551
	11th to 20th	Night	6% 11% 4 12% 6% 5% 5% 4 6% 7% 34%	2660
	21st to end	Night	7% 13% 5% 11% 5% 5% 4 4 5% 7% 36%	2660
December	1st to 10th	Night	7% 12% 4 12% 9% 6% 6% 4 4 6% 29%	2744
	11th to 20th	Night	6% 12% 5% 12% 7% 7% 6% 4 6% 7% 28%	3511
	21st to end	Night	4 7% 3 7% 5% 4 4 3 5% 6% 52%	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% 15% 16% 9%	1498
March	1st to 10th	Day	54% 7% 13% 22% 4	3130
	11th to 20th	Day	42% 10% 22% 21% 5%	3426
	21st to end	Day	58% 7% 16% 12% 6%	4038
April	1st to 10th	Day	44% 8% 15% 22% 11% 1	2280
	11th to 20th	Day	53% 6% 15% 19% 6% 1	2259
	21st to end	Day	46% 6% 15% 23% 9% 1	2617
May	1st to 10th	Day	50% 6% 14% 22% 7% 1	4430
	11th to 20th	Day	39% 9% 15% 27% 11%	4392
	21st to end	Day	44% 9% 17% 23% 6%	4825
June	1st to 10th	Day	42% 7% 17% 24% 9% 1	2783
	11th to 20th	Day	47% 7% 15% 21% 10% 1	2850
	21st to end	Day	33% 7% 19% 32% 9% 1	2850
July	1st to 10th	Day	31% 6% 22% 25% 15% 1	4666
	11th to 20th	Day	21% 6% 16% 36% 19% 3	4552
	21st to end	Day	19% 4 9% 36% 24% 9%	4651
August	1st to 10th	Day	31% 4 14% 31% 19% 2	4396
	11th to 20th	Day	26% 4 18% 36% 15% 1	4232
	21st to end	Day	27% 3 12% 40% 16% 2	4308
September	1st to 10th	Day	33% 5% 14% 27% 17% 4	2280
	11th to 20th	Day	36% 5% 16% 27% 13% 3	2280
	21st to end	Day	36% 4 12% 29% 16% 2	2033
October	1st to 10th	Day	41% 4 15% 26% 13% 1	1900
	11th to 20th	Day	39% 5% 14% 30% 11% 1	1883
	21st to end	Day	44% 5% 18% 25% 7%	1881
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	47% 5% 12% 24% 11%	1956
March	1st to 10th	Night	48% 7% 16% 21% 7%	3734
	11th to 20th	Night	40% 7% 23% 24% 6% 1	3537
	21st to end	Night	58% 6% 16% 15% 6%	3607
April	1st to 10th	Night	39% 6% 15% 26% 13% 1	1900
	11th to 20th	Night	48% 5% 13% 19% 12% 2	1870
	21st to end	Night	43% 6% 13% 26% 11%	1563
May	1st to 10th	Night	47% 8% 10% 24% 10% 1	2540
	11th to 20th	Night	36% 7% 14% 28% 14% 1	2518
	21st to end	Night	38% 10% 15% 30% 6%	2762
June	1st to 10th	Night	35% 6% 17% 27% 13% 2	1393
	11th to 20th	Night	35% 6% 18% 24% 14% 2	1330
	21st to end	Night	29% 8% 17% 33% 12% 1	1330
July	1st to 10th	Night	26% 6% 26% 29% 13% 1	2185
	11th to 20th	Night	23% 4 15% 30% 24% 3	2274
	21st to end	Night	17% 3 11% 39% 21% 8%	2674
August	1st to 10th	Night	26% 3 14% 35% 21% 1	2520
	11th to 20th	Night	23% 4 15% 39% 17% 1	2670
	21st to end	Night	26% 4 14% 35% 18% 3	3358
September	1st to 10th	Night	29% 4 11% 30% 20% 6%	1900
	11th to 20th	Night	32% 5% 13% 28% 18% 3	1900
	21st to end	Night	32% 4 12% 32% 18% 2	2146
October	1st to 10th	Night	36% 5% 16% 26% 16% 1	2280
	11th to 20th	Night	35% 4 14% 32% 13% 1	2280
	21st to end	Night	44% 6% 14% 26% 9% 2	2714
November	1st to 10th	Night	50% 5% 14% 20% 9% 2	2551
	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% 36% 33% 15% 3	225
March	1st to 10th	Day	13% 8% 35% 30% 13% 2	270
	11th to 20th	Day	12% 13% 34% 24% 12% 5%	422
	21st to end	Day	14% 9% 35% 24% 13% 5%	506
April	1st to 10th	Day	11% 16% 39% 28% 6%	460
	11th to 20th	Day	18% 13% 34% 27% 6% 2	452
	21st to end	Day	19% 10% 28% 30% 12% 1	607
May	1st to 10th	Day	15% 6% 25% 31% 18% 5%	653
	11th to 20th	Day	14% 8% 24% 29% 19% 7%	675
	21st to end	Day	16% 8% 24% 26% 20% 6%	734
June	1st to 10th	Day	16% 12% 25% 27% 15% 5%	680
	11th to 20th	Day	17% 13% 32% 23% 12% 3	680
	21st to end	Day	11% 6% 26% 31% 20% 6%	680
July	1st to 10th	Day	6% 4 26% 34% 23% 6%	671
	11th to 20th	Day	6% 5% 26% 38% 20% 5%	668
	21st to end	Day	5% 5% 26% 32% 25% 6%	739
August	1st to 10th	Day	10% 4 22% 37% 21% 7%	676
	11th to 20th	Day	11% 4 23% 31% 23% 8%	577
	21st to end	Day	11% 6% 22% 36% 19% 6%	539
September	1st to 10th	Day	11% 8% 30% 30% 17% 5%	490
	11th to 20th	Day	14% 9% 27% 33% 14% 3	490
	21st to end	Day	16% 10% 27% 30% 12% 4	329
October	1st to 10th	Day	21% 6% 25% 25% 20% 2	300
	11th to 20th	Day	10% 11% 34% 28% 12% 4	300
	21st to end	Day	15% 11% 40% 24% 8% 2	330
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% 30% 33% 17% 4	628
March	1st to 10th	Night	10% 9% 34% 34% 11% 2	760
	11th to 20th	Night	11% 9% 36% 32% 11% 2	760
	21st to end	Night	14% 7% 27% 37% 14% 1	705
April	1st to 10th	Night	10% 10% 32% 38% 11%	570
	11th to 20th	Night	15% 8% 37% 32% 8%	563
	21st to end	Night	17% 8% 30% 36% 9%	570
May	1st to 10th	Night	15% 5% 26% 37% 15% 1	570
	11th to 20th	Night	15% 6% 25% 35% 17% 2	561
	21st to end	Night	19% 8% 22% 32% 18% 1	617
June	1st to 10th	Night	13% 8% 29% 35% 14% 2	443
	11th to 20th	Night	16% 6% 27% 38% 13%	380
	21st to end	Night	12% 4 26% 39% 16% 2	380
July	1st to 10th	Night	8% 3 23% 45% 20% 1	370
	11th to 20th	Night	8% 3 28% 45% 16% 1	425
	21st to end	Night	3 4 29% 48% 16% 1	624
August	1st to 10th	Night	8% 3 23% 46% 17% 3	567
	11th to 20th	Night	6% 4 21% 45% 23% 2	564
	21st to end	Night	10% 3 25% 42% 19% 1	627
September	1st to 10th	Night	10% 4 25% 44% 16% 2	570
	11th to 20th	Night	10% 5% 24% 44% 16% 1	570
	21st to end	Night	12% 5% 30% 40% 12% 1	655
October	1st to 10th	Night	18% 7% 28% 34% 13% 1	760
	11th to 20th	Night	13% 6% 33% 34% 13% 2	760
	21st to end	Night	14% 9% 38% 31% 8%	1042
November	1st to 10th	Night	21% 9% 35% 29% 6% 1	928
	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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