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 2026-09-29.

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	8% 7% 3 8% 5% 5% 5% 4 6% 8% 41%	158621
	Night	7% 8% 3 9% 5% 5% 5% 4 6% 8% 40%	150199
Transparency	Day	41% 5% 15% 26% 12% 2	153205
	Night	42% 5% 15% 25% 12% 2	146625
Seeing	Day	13% 9% 30% 29% 15% 4	18572
	Night	12% 8% 33% 34% 12% 1	27873

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% 13% 5% 13% 8% 7% 7% 4 5% 6% 27%	4124
	11th to 20th	Day	2 7% 4 12% 8% 8% 10% 7% 7% 7% 26%	4536
	21st to end	Day	4 9% 4 11% 7% 6% 6% 4 6% 7% 35%	5188
February	1st to 10th	Day	8% 13% 6% 11% 8% 5% 7% 3 6% 7% 25%	1821
	11th to 20th	Day	6% 12% 4 10% 7% 7% 6% 5% 6% 6% 28%	1845
	21st to end	Day	4 12% 4 12% 7% 6% 6% 6% 6% 8% 29%	1651
March	1st to 10th	Day	5% 12% 6% 15% 6% 5% 3 3 5% 7% 33%	4600
	11th to 20th	Day	5% 11% 5% 12% 6% 5% 5% 4 7% 9% 32%	5016
	21st to end	Day	7% 15% 6% 15% 6% 5% 5% 4 6% 7% 24%	5918
April	1st to 10th	Day	8% 11% 4 8% 5% 5% 5% 4 6% 8% 36%	2520
	11th to 20th	Day	12% 13% 4 9% 5% 5% 5% 4 6% 8% 28%	2496
	21st to end	Day	16% 9% 3 7% 4 4 5% 4 4 7% 37%	2893
May	1st to 10th	Day	12% 8% 3 6% 4 4 5% 4 5% 7% 42%	8224
	11th to 20th	Day	15% 9% 3 8% 5% 5% 5% 5% 6% 8% 32%	8191
	21st to end	Day	11% 5% 2 6% 5% 5% 5% 4 6% 8% 44%	9026
June	1st to 10th	Day	15% 6% 2 6% 5% 4 5% 5% 7% 7% 38%	3076
	11th to 20th	Day	16% 7% 2 7% 6% 5% 5% 4 6% 7% 34%	3150
	21st to end	Day	10% 5% 2 5% 4 5% 5% 4 7% 9% 44%	3150
July	1st to 10th	Day	4 4 1 5% 4 5% 6% 5% 7% 9% 49%	8819
	11th to 20th	Day	6% 4 2 5% 4 4 5% 5% 7% 10% 47%	8635
	21st to end	Day	5% 3 2 4 3 3 4 4 5% 7% 61%	8957
August	1st to 10th	Day	8% 5% 2 6% 4 5% 4 4 5% 6% 50%	8142
	11th to 20th	Day	8% 4 1 5% 4 4 5% 4 7% 10% 50%	7867
	21st to end	Day	7% 4 2 5% 3 4 4 3 5% 7% 58%	7980
September	1st to 10th	Day	10% 5% 2 5% 5% 4 4 4 5% 7% 50%	2520
	11th to 20th	Day	12% 7% 2 6% 4 3 4 3 5% 7% 45%	2520
	21st to end	Day	12% 5% 2 5% 3 4 3 3 5% 7% 51%	2226
October	1st to 10th	Day	9% 5% 2 5% 3 4 4 3 5% 7% 54%	3270
	11th to 20th	Day	7% 6% 3 5% 4 3 3 3 6% 10% 50%	3220
	21st to end	Day	5% 8% 3 7% 4 5% 5% 5% 6% 8% 44%	3190
November	1st to 10th	Day	11% 13% 4 8% 6% 4 4 4 5% 7% 34%	1695
	11th to 20th	Day	6% 12% 5% 13% 6% 5% 4 4 6% 6% 34%	1680
	21st to end	Day	9% 11% 5% 8% 7% 7% 5% 5% 6% 6% 31%	1680
December	1st to 10th	Day	4 10% 5% 14% 8% 7% 6% 4 6% 7% 28%	2532
	11th to 20th	Day	8% 13% 6% 14% 7% 5% 6% 5% 7% 6% 23%	2688
	21st to end	Day	6% 7% 3 8% 7% 4 5% 3 5% 8% 43%	3575
January	1st to 10th	Night	3 10% 5% 13% 8% 6% 7% 5% 6% 6% 30%	8768
	11th to 20th	Night	3 8% 4 12% 8% 8% 7% 5% 9% 8% 27%	8441
	21st to end	Night	4 11% 5% 12% 7% 5% 5% 4 7% 8% 33%	9026
February	1st to 10th	Night	6% 13% 5% 10% 7% 7% 6% 5% 7% 7% 27%	2819
	11th to 20th	Night	6% 12% 4 11% 7% 5% 5% 4 7% 7% 33%	2662
	21st to end	Night	5% 9% 4 9% 6% 6% 6% 4 6% 8% 37%	2154
March	1st to 10th	Night	5% 8% 3 12% 8% 6% 5% 4 6% 9% 34%	5494
	11th to 20th	Night	6% 10% 4 10% 5% 5% 5% 5% 6% 8% 37%	5185
	21st to end	Night	8% 13% 7% 16% 7% 5% 6% 4 6% 7% 22%	5284
April	1st to 10th	Night	6% 10% 3 8% 5% 4 4 4 7% 8% 39%	2100
	11th to 20th	Night	12% 11% 4 8% 4 4 4 4 6% 8% 33%	2069
	21st to end	Night	11% 8% 3 8% 5% 4 5% 5% 7% 8% 36%	1727
May	1st to 10th	Night	11% 6% 2 6% 4 4 4 4 6% 8% 45%	4723
	11th to 20th	Night	17% 8% 3 7% 4 5% 5% 4 6% 8% 35%	4701
	21st to end	Night	11% 5% 2 5% 4 5% 5% 5% 7% 9% 44%	5181
June	1st to 10th	Night	12% 5% 2 5% 3 3 5% 4 7% 8% 45%	1539
	11th to 20th	Night	12% 6% 2 6% 4 3 5% 5% 6% 10% 41%	1470
	21st to end	Night	9% 5% 2 6% 4 4 5% 3 6% 8% 50%	1470
July	1st to 10th	Night	5% 4 1 5% 4 4 5% 4 7% 10% 51%	4140
	11th to 20th	Night	9% 5% 2 5% 4 5% 4 4 6% 7% 49%	4320
	21st to end	Night	4 3 1 4 3 3 4 4 7% 9% 58%	5152
August	1st to 10th	Night	7% 5% 2 5% 3 3 4 4 7% 9% 52%	4680
	11th to 20th	Night	6% 3 1 4 4 4 5% 4 7% 11% 50%	4986
	21st to end	Night	7% 4 2 4 4 4 5% 4 5% 6% 55%	6236
September	1st to 10th	Night	9% 4 1 4 4 3 4 3 4 7% 56%	2100
	11th to 20th	Night	10% 5% 2 5% 4 4 4 4 5% 8% 49%	2100
	21st to end	Night	10% 4 1 5% 3 3 4 3 5% 7% 56%	2348
October	1st to 10th	Night	9% 6% 2 5% 3 3 4 3 5% 7% 54%	3920
	11th to 20th	Night	5% 5% 2 5% 3 3 3 3 5% 11% 53%	3898
	21st to end	Night	6% 8% 2 6% 4 4 5% 4 7% 8% 45%	4607
November	1st to 10th	Night	12% 14% 4 8% 5% 4 4 4 5% 5% 35%	2820
	11th to 20th	Night	6% 11% 4 11% 6% 6% 5% 4 6% 7% 34%	2940
	21st to end	Night	6% 13% 5% 11% 6% 5% 5% 4 5% 7% 34%	2940
December	1st to 10th	Night	7% 14% 6% 14% 8% 6% 5% 3 4 6% 26%	4869
	11th to 20th	Night	5% 13% 6% 14% 8% 7% 6% 4 5% 6% 25%	5707
	21st to end	Night	3 8% 4 10% 7% 4 4 3 5% 6% 46%	7623

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	59% 4 13% 17% 7%	4125
	11th to 20th	Day	54% 6% 15% 17% 9%	4536
	21st to end	Day	48% 4 21% 21% 5%	5188
February	1st to 10th	Day	58% 5% 10% 18% 10%	1821
	11th to 20th	Day	53% 5% 13% 15% 13% 1	1854
	21st to end	Day	51% 7% 15% 18% 9%	1651
March	1st to 10th	Day	50% 5% 18% 20% 6%	4600
	11th to 20th	Day	46% 7% 18% 24% 4	5016
	21st to end	Day	58% 6% 15% 14% 6%	5918
April	1st to 10th	Day	45% 7% 15% 22% 11% 1	2520
	11th to 20th	Day	53% 6% 15% 19% 6% 1	2499
	21st to end	Day	46% 5% 15% 24% 9% 1	2893
May	1st to 10th	Day	41% 4 10% 30% 14% 2	8224
	11th to 20th	Day	47% 6% 13% 22% 12%	8195
	21st to end	Day	36% 5% 12% 30% 15% 1	9027
June	1st to 10th	Day	42% 6% 16% 24% 9% 2	3076
	11th to 20th	Day	47% 6% 15% 21% 10% 1	3150
	21st to end	Day	34% 6% 18% 32% 9% 1	3150
July	1st to 10th	Day	29% 5% 23% 27% 15% 1	8746
	11th to 20th	Day	31% 5% 15% 31% 15% 3	8554
	21st to end	Day	24% 4 11% 31% 21% 10%	8759
August	1st to 10th	Day	29% 3 13% 32% 20% 2	6446
	11th to 20th	Day	32% 4 21% 32% 11% 1	6204
	21st to end	Day	29% 3 12% 40% 16% 1	6259
September	1st to 10th	Day	33% 4 14% 28% 16% 3	2520
	11th to 20th	Day	37% 5% 17% 27% 12% 3	2520
	21st to end	Day	34% 4 12% 31% 17% 2	2226
October	1st to 10th	Day	32% 3 11% 36% 16% 3	3270
	11th to 20th	Day	31% 3 14% 37% 13% 2	3220
	21st to end	Day	37% 4 16% 34% 9%	3190
November	1st to 10th	Day	50% 5% 14% 22% 8% 1	1695
	11th to 20th	Day	50% 6% 15% 21% 7% 1	1680
	21st to end	Day	52% 7% 20% 17% 5%	1680
December	1st to 10th	Day	54% 6% 21% 14% 5%	2532
	11th to 20th	Day	60% 5% 22% 9% 4	2686
	21st to end	Day	40% 4 11% 28% 12% 5%	3575
January	1st to 10th	Night	53% 5% 16% 19% 8%	8769
	11th to 20th	Night	51% 4 17% 17% 10% 1	8441
	21st to end	Night	49% 4 20% 20% 7%	9026
February	1st to 10th	Night	53% 6% 13% 18% 9% 1	2819
	11th to 20th	Night	50% 5% 15% 17% 12% 1	2663
	21st to end	Night	45% 5% 13% 25% 11%	2154
March	1st to 10th	Night	44% 6% 19% 21% 10%	5494
	11th to 20th	Night	45% 6% 18% 25% 7%	5185
	21st to end	Night	61% 5% 13% 15% 5%	5284
April	1st to 10th	Night	40% 6% 14% 26% 13% 1	2100
	11th to 20th	Night	47% 5% 13% 21% 12% 2	2069
	21st to end	Night	44% 6% 13% 26% 11%	1727
May	1st to 10th	Night	35% 5% 10% 30% 19% 1	4724
	11th to 20th	Night	46% 5% 13% 22% 14% 1	4702
	21st to end	Night	34% 7% 12% 31% 14% 2	5182
June	1st to 10th	Night	34% 6% 16% 27% 15% 2	1539
	11th to 20th	Night	37% 6% 17% 25% 13% 1	1470
	21st to end	Night	31% 7% 17% 33% 11% 1	1470
July	1st to 10th	Night	28% 4 26% 27% 13% 2	4105
	11th to 20th	Night	33% 4 13% 28% 18% 4	4278
	21st to end	Night	22% 3 14% 33% 19% 8%	5038
August	1st to 10th	Night	22% 3 16% 38% 19% 2	3700
	11th to 20th	Night	29% 4 21% 33% 12% 1	3925
	21st to end	Night	31% 3 13% 31% 20% 2	4888
September	1st to 10th	Night	29% 4 11% 32% 20% 6%	2100
	11th to 20th	Night	33% 5% 15% 27% 17% 3	2100
	21st to end	Night	30% 4 12% 33% 20% 2	2348
October	1st to 10th	Night	31% 3 13% 31% 20% 2	3920
	11th to 20th	Night	27% 3 13% 41% 15% 1	3898
	21st to end	Night	36% 4 11% 36% 12% 1	4607
November	1st to 10th	Night	50% 5% 14% 20% 9% 2	2820
	11th to 20th	Night	49% 4 18% 21% 7% 1	2940
	21st to end	Night	50% 5% 19% 20% 6%	2940
December	1st to 10th	Night	61% 4 18% 12% 4	4869
	11th to 20th	Night	60% 5% 18% 14% 3	5708
	21st to end	Night	40% 3 11% 26% 15% 4	7623

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	10% 13% 34% 27% 13% 4	220
	11th to 20th	Day	11% 12% 36% 26% 12% 3	292
	21st to end	Day	12% 13% 34% 29% 10% 2	363
February	1st to 10th	Day	15% 10% 42% 24% 7% 1	330
	11th to 20th	Day	9% 9% 38% 28% 14% 2	330
	21st to end	Day	5% 11% 39% 30% 13% 2	273
March	1st to 10th	Day	11% 8% 35% 31% 12% 2	330
	11th to 20th	Day	11% 13% 35% 26% 11% 4	498
	21st to end	Day	14% 9% 37% 25% 12% 4	594
April	1st to 10th	Day	12% 14% 39% 29% 6% 1	540
	11th to 20th	Day	18% 13% 34% 27% 6% 2	532
	21st to end	Day	18% 10% 27% 31% 13% 2	703
May	1st to 10th	Day	15% 7% 25% 32% 18% 5%	753
	11th to 20th	Day	17% 9% 24% 27% 17% 6%	775
	21st to end	Day	15% 8% 24% 28% 19% 6%	844
June	1st to 10th	Day	16% 13% 26% 25% 15% 5%	780
	11th to 20th	Day	17% 13% 32% 24% 12% 3	780
	21st to end	Day	13% 6% 27% 30% 19% 5%	780
July	1st to 10th	Day	6% 4 26% 35% 23% 5%	771
	11th to 20th	Day	7% 6% 27% 37% 19% 5%	768
	21st to end	Day	6% 5% 27% 34% 24% 6%	849
August	1st to 10th	Day	10% 5% 22% 36% 21% 6%	776
	11th to 20th	Day	11% 4 24% 31% 22% 7%	667
	21st to end	Day	11% 6% 22% 35% 19% 7%	627
September	1st to 10th	Day	12% 8% 29% 30% 16% 5%	570
	11th to 20th	Day	14% 8% 26% 34% 14% 3	570
	21st to end	Day	15% 10% 25% 34% 13% 4	386
October	1st to 10th	Day	19% 8% 25% 26% 20% 2	330
	11th to 20th	Day	12% 12% 34% 27% 11% 4	330
	21st to end	Day	14% 11% 40% 25% 8% 2	363
November	1st to 10th	Day	18% 10% 37% 22% 11% 2	330
	11th to 20th	Day	13% 15% 34% 26% 11% 1	330
	21st to end	Day	11% 11% 38% 26% 13% 2	330
December	1st to 10th	Day	12% 12% 45% 23% 7% 2	330
	11th to 20th	Day	14% 14% 40% 23% 9% 1	286
	21st to end	Day	12% 7% 35% 33% 10% 2	242
January	1st to 10th	Night	8% 14% 40% 30% 9%	1050
	11th to 20th	Night	10% 14% 39% 28% 7% 1	1050
	21st to end	Night	12% 12% 40% 27% 9% 1	1155
February	1st to 10th	Night	11% 11% 34% 30% 13% 2	929
	11th to 20th	Night	11% 9% 39% 31% 9% 1	824
	21st to end	Night	7% 9% 32% 32% 16% 4	692
March	1st to 10th	Night	10% 9% 35% 33% 11% 2	840
	11th to 20th	Night	11% 9% 36% 33% 10% 1	840
	21st to end	Night	14% 7% 29% 36% 13% 1	779
April	1st to 10th	Night	10% 9% 32% 38% 10%	630
	11th to 20th	Night	15% 8% 38% 32% 7%	623
	21st to end	Night	17% 8% 31% 36% 8%	630
May	1st to 10th	Night	14% 5% 27% 39% 14% 1	630
	11th to 20th	Night	17% 7% 24% 33% 16% 2	621
	21st to end	Night	18% 8% 24% 32% 17% 1	683
June	1st to 10th	Night	12% 8% 30% 34% 14% 2	489
	11th to 20th	Night	15% 6% 29% 38% 12%	420
	21st to end	Night	13% 4 27% 39% 15% 2	420
July	1st to 10th	Night	8% 3 23% 45% 20%	410
	11th to 20th	Night	9% 4 27% 46% 14% 1	471
	21st to end	Night	3 3 28% 49% 15% 1	690
August	1st to 10th	Night	8% 3 23% 47% 17% 2	627
	11th to 20th	Night	6% 4 22% 45% 21% 1	624
	21st to end	Night	9% 4 25% 42% 19% 1	693
September	1st to 10th	Night	10% 3 24% 45% 16% 2	630
	11th to 20th	Night	10% 4 25% 44% 16% 1	630
	21st to end	Night	11% 5% 29% 42% 12% 1	716
October	1st to 10th	Night	17% 6% 28% 35% 13% 1	800
	11th to 20th	Night	13% 7% 34% 33% 12% 2	800
	21st to end	Night	14% 10% 38% 30% 7%	1097
November	1st to 10th	Night	20% 10% 35% 29% 5% 1	1025
	11th to 20th	Night	12% 11% 41% 26% 9% 1	1050
	21st to end	Night	12% 10% 45% 25% 7% 1	1050
December	1st to 10th	Night	13% 9% 39% 27% 10% 2	1050
	11th to 20th	Night	13% 13% 37% 28% 9% 1	1050
	21st to end	Night	11% 8% 37% 32% 10% 2	1155

Page generated at 2026-09-26 02:18:42. Version ac07

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