Yorkton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Yorkton clear sky chart from 2005-11-06 to 2024-02-15.

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	11% 9% 4 7% 7% 4 5% 5% 6% 7% 35%	78341
	Night	9% 9% 4 9% 7% 4 5% 5% 6% 7% 35%	80724
Transparency	Day	48% 4 15% 24% 8% 1	78052
	Night	48% 4 14% 23% 9% 1	80593
Seeing	Day	15% 7% 28% 30% 15% 4	15182
	Night	14% 7% 30% 34% 14% 2	24870

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	6% 14% 7% 13% 10% 6% 7% 5% 6% 7% 18%	2219
	11th to 20th	Day	5% 9% 5% 11% 14% 7% 9% 10% 9% 7% 13%	2516
	21st to end	Day	8% 12% 5% 12% 11% 3 5% 6% 4 5% 30%	2794
February	1st to 10th	Day	9% 11% 4 11% 10% 5% 7% 7% 6% 8% 23%	1520
	11th to 20th	Day	7% 11% 5% 9% 8% 6% 8% 6% 6% 8% 26%	1578
	21st to end	Day	6% 9% 7% 10% 11% 6% 6% 6% 7% 7% 25%	1480
March	1st to 10th	Day	12% 13% 5% 10% 10% 6% 7% 4 6% 6% 21%	1800
	11th to 20th	Day	9% 12% 7% 10% 6% 4 6% 5% 5% 8% 28%	1840
	21st to end	Day	11% 12% 5% 9% 7% 4 5% 4 6% 8% 29%	2360
April	1st to 10th	Day	8% 8% 5% 8% 7% 5% 4 5% 4 8% 38%	2160
	11th to 20th	Day	14% 13% 5% 9% 8% 4 4 4 6% 6% 28%	2245
	21st to end	Day	14% 7% 3 6% 6% 3 6% 5% 5% 7% 37%	2405
May	1st to 10th	Day	14% 8% 4 6% 6% 3 5% 4 5% 6% 39%	2520
	11th to 20th	Day	12% 7% 3 6% 5% 3 5% 4 5% 8% 42%	2533
	21st to end	Day	19% 8% 3 6% 5% 3 5% 5% 5% 8% 33%	2918
June	1st to 10th	Day	17% 6% 2 5% 5% 3 5% 4 6% 9% 38%	2700
	11th to 20th	Day	20% 7% 3 6% 6% 3 5% 6% 6% 7% 30%	2854
	21st to end	Day	14% 6% 2 5% 5% 3 5% 6% 7% 8% 39%	2880
July	1st to 10th	Day	8% 4 2 5% 5% 3 5% 6% 6% 9% 47%	2858
	11th to 20th	Day	11% 5% 2 4 6% 3 6% 5% 7% 8% 44%	2653
	21st to end	Day	8% 5% 2 4 5% 3 4 6% 6% 9% 49%	2742
August	1st to 10th	Day	8% 5% 2 5% 5% 4 6% 5% 7% 8% 45%	2507
	11th to 20th	Day	12% 4 2 4 5% 3 4 5% 7% 9% 45%	2459
	21st to end	Day	14% 5% 2 4 5% 2 4 5% 5% 7% 47%	2502
September	1st to 10th	Day	11% 5% 2 5% 4 3 4 5% 6% 7% 48%	2160
	11th to 20th	Day	13% 8% 2 6% 5% 3 4 4 5% 7% 43%	2080
	21st to end	Day	13% 7% 3 6% 5% 3 4 4 4 6% 47%	1980
October	1st to 10th	Day	17% 12% 3 6% 5% 2 4 3 4 7% 36%	1872
	11th to 20th	Day	9% 11% 5% 8% 6% 3 4 4 5% 6% 38%	1639
	21st to end	Day	12% 14% 6% 9% 6% 3 5% 4 5% 5% 29%	1782
November	1st to 10th	Day	19% 14% 7% 9% 7% 2 4 4 3 5% 25%	1631
	11th to 20th	Day	9% 15% 7% 12% 9% 4 5% 5% 5% 6% 23%	1373
	21st to end	Day	11% 13% 6% 10% 9% 3 5% 4 4 5% 28%	1330
December	1st to 10th	Day	7% 11% 5% 13% 9% 6% 7% 7% 6% 7% 22%	1330
	11th to 20th	Day	10% 15% 7% 14% 9% 5% 7% 5% 4 6% 18%	1679
	21st to end	Day	5% 7% 4 6% 7% 4 5% 5% 5% 6% 46%	2442
January	1st to 10th	Night	5% 13% 7% 16% 10% 4 6% 5% 6% 6% 21%	4733
	11th to 20th	Night	5% 8% 5% 14% 14% 6% 8% 9% 7% 7% 16%	4392
	21st to end	Night	6% 11% 6% 13% 8% 4 5% 5% 5% 6% 30%	4873
February	1st to 10th	Night	10% 11% 5% 8% 9% 4 7% 6% 7% 7% 27%	2660
	11th to 20th	Night	5% 10% 4 9% 8% 4 7% 7% 7% 7% 31%	2378
	21st to end	Night	5% 7% 6% 10% 8% 4 6% 6% 5% 7% 36%	1776
March	1st to 10th	Night	11% 11% 5% 9% 7% 4 6% 5% 5% 7% 29%	2160
	11th to 20th	Night	7% 8% 4 8% 7% 5% 5% 5% 6% 8% 35%	2119
	21st to end	Night	9% 11% 4 7% 7% 4 5% 5% 6% 7% 35%	1994
April	1st to 10th	Night	5% 7% 4 7% 5% 4 6% 4 6% 7% 43%	1800
	11th to 20th	Night	15% 10% 5% 7% 6% 4 5% 5% 5% 6% 33%	1665
	21st to end	Night	15% 8% 3 6% 6% 4 5% 6% 6% 6% 35%	1553
May	1st to 10th	Night	13% 9% 3 6% 6% 2 4 4 6% 7% 41%	1440
	11th to 20th	Night	15% 5% 2 5% 5% 3 5% 5% 6% 8% 41%	1361
	21st to end	Night	18% 5% 2 5% 5% 3 4 6% 6% 8% 37%	1358
June	1st to 10th	Night	14% 6% 3 5% 5% 4 5% 5% 5% 7% 43%	1260
	11th to 20th	Night	18% 5% 2 5% 4 4 4 5% 5% 9% 39%	1100
	21st to end	Night	11% 6% 2 6% 6% 3 6% 4 5% 9% 43%	1080
July	1st to 10th	Night	8% 3 1 4 4 3 5% 4 6% 10% 50%	1099
	11th to 20th	Night	8% 3 2 4 4 2 4 5% 6% 8% 54%	1304
	21st to end	Night	5% 3 2 3 3 2 3 3 5% 8% 62%	1576
August	1st to 10th	Night	6% 4 1 4 4 3 4 5% 6% 8% 56%	1432
	11th to 20th	Night	9% 4 1 3 3 2 5% 4 5% 8% 55%	1442
	21st to end	Night	11% 5% 2 4 3 3 4 4 5% 7% 52%	1852
September	1st to 10th	Night	8% 6% 2 5% 4 3 5% 6% 6% 8% 48%	1800
	11th to 20th	Night	13% 7% 2 4 4 2 4 4 6% 7% 46%	1880
	21st to end	Night	11% 6% 3 6% 3 2 4 4 7% 8% 47%	1980
October	1st to 10th	Night	17% 9% 3 6% 4 2 4 3 4 6% 41%	2088
	11th to 20th	Night	10% 10% 4 5% 6% 3 5% 5% 6% 6% 41%	2302
	21st to end	Night	12% 12% 6% 9% 6% 2 4 5% 5% 6% 33%	2574
November	1st to 10th	Night	13% 14% 6% 8% 7% 4 4 5% 4 6% 27%	2443
	11th to 20th	Night	9% 14% 6% 12% 10% 4 5% 5% 4 6% 26%	2807
	21st to end	Night	9% 12% 6% 11% 10% 4 4 5% 5% 8% 28%	2850
December	1st to 10th	Night	7% 10% 6% 12% 9% 5% 5% 6% 6% 7% 25%	2850
	11th to 20th	Night	8% 14% 7% 14% 8% 5% 6% 6% 6% 6% 20%	3518
	21st to end	Night	5% 7% 4 8% 7% 4 5% 5% 5% 6% 45%	5225

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	65% 4 14% 13% 4	2219
	11th to 20th	Day	63% 4 12% 17% 4	2540
	21st to end	Day	57% 4 9% 24% 6%	2794
February	1st to 10th	Day	59% 4 15% 15% 6%	1520
	11th to 20th	Day	53% 4 11% 22% 11%	1586
	21st to end	Day	55% 3 11% 21% 10%	1480
March	1st to 10th	Day	62% 5% 11% 16% 6%	1800
	11th to 20th	Day	54% 5% 13% 21% 6%	1841
	21st to end	Day	53% 4 14% 21% 7%	2360
April	1st to 10th	Day	46% 4 14% 24% 11% 1	2160
	11th to 20th	Day	55% 4 13% 18% 8% 2	2245
	21st to end	Day	45% 5% 17% 23% 9%	2405
May	1st to 10th	Day	45% 4 11% 27% 13% 1	2520
	11th to 20th	Day	41% 5% 12% 27% 15% 1	2537
	21st to end	Day	50% 5% 12% 22% 11% 1	2918
June	1st to 10th	Day	44% 4 16% 27% 9% 1	2700
	11th to 20th	Day	51% 6% 14% 19% 9% 1	2854
	21st to end	Day	42% 5% 19% 27% 7%	2880
July	1st to 10th	Day	31% 6% 23% 32% 8%	2780
	11th to 20th	Day	38% 5% 18% 30% 8% 1	2572
	21st to end	Day	31% 5% 21% 36% 7%	2590
August	1st to 10th	Day	35% 5% 20% 29% 10%	2491
	11th to 20th	Day	34% 6% 22% 33% 5%	2459
	21st to end	Day	37% 5% 17% 33% 9%	2502
September	1st to 10th	Day	35% 4 19% 30% 12% 1	2160
	11th to 20th	Day	42% 4 16% 27% 9% 1	2080
	21st to end	Day	40% 3 12% 31% 12% 1	1980
October	1st to 10th	Day	50% 3 15% 25% 7% 1	1872
	11th to 20th	Day	47% 4 11% 29% 8%	1639
	21st to end	Day	57% 4 14% 20% 6% 1	1782
November	1st to 10th	Day	62% 4 11% 16% 6%	1631
	11th to 20th	Day	62% 5% 15% 12% 6%	1373
	21st to end	Day	59% 5% 13% 19% 4	1330
December	1st to 10th	Day	61% 5% 12% 16% 6%	1330
	11th to 20th	Day	68% 5% 13% 11% 3	1680
	21st to end	Day	39% 3 14% 24% 14% 6%	2442
January	1st to 10th	Night	63% 4 13% 15% 5%	4733
	11th to 20th	Night	65% 4 15% 12% 4	4430
	21st to end	Night	55% 4 15% 20% 6%	4873
February	1st to 10th	Night	54% 4 12% 19% 10% 1	2660
	11th to 20th	Night	49% 4 14% 22% 10% 1	2380
	21st to end	Night	47% 3 12% 27% 10%	1776
March	1st to 10th	Night	54% 3 13% 22% 7%	2160
	11th to 20th	Night	45% 5% 15% 26% 8% 1	2119
	21st to end	Night	47% 5% 14% 23% 10% 1	1994
April	1st to 10th	Night	39% 3 13% 27% 18% 1	1800
	11th to 20th	Night	50% 4 10% 22% 12% 2	1665
	21st to end	Night	48% 5% 12% 22% 12% 1	1553
May	1st to 10th	Night	42% 4 10% 26% 17% 1	1440
	11th to 20th	Night	40% 4 11% 26% 16% 2	1361
	21st to end	Night	45% 5% 13% 24% 13% 1	1358
June	1st to 10th	Night	41% 5% 15% 26% 12% 2	1260
	11th to 20th	Night	43% 5% 19% 18% 14% 2	1100
	21st to end	Night	40% 6% 20% 27% 7% 1	1080
July	1st to 10th	Night	29% 5% 20% 34% 12%	1068
	11th to 20th	Night	28% 5% 19% 34% 13% 1	1262
	21st to end	Night	22% 4 21% 40% 11% 1	1488
August	1st to 10th	Night	25% 6% 23% 34% 12%	1424
	11th to 20th	Night	28% 4 22% 33% 11% 1	1442
	21st to end	Night	32% 4 12% 39% 12% 1	1852
September	1st to 10th	Night	32% 6% 15% 32% 14% 2	1800
	11th to 20th	Night	37% 4 16% 30% 12% 1	1880
	21st to end	Night	35% 4 14% 32% 14% 1	1980
October	1st to 10th	Night	46% 3 18% 24% 8% 1	2088
	11th to 20th	Night	43% 4 13% 30% 10%	2302
	21st to end	Night	52% 5% 13% 24% 6%	2574
November	1st to 10th	Night	58% 4 14% 16% 7% 1	2443
	11th to 20th	Night	61% 4 16% 14% 5%	2807
	21st to end	Night	56% 4 18% 17% 5%	2850
December	1st to 10th	Night	57% 4 13% 18% 6% 1	2850
	11th to 20th	Night	63% 4 12% 15% 5%	3516
	21st to end	Night	41% 3 12% 22% 17% 5%	5225

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	15% 6% 32% 26% 18% 3	270
	11th to 20th	Day	8% 5% 34% 38% 14% 1	270
	21st to end	Day	16% 7% 26% 34% 14% 2	297
February	1st to 10th	Day	14% 6% 34% 34% 11% 1	270
	11th to 20th	Day	9% 6% 34% 32% 17% 3	252
	21st to end	Day	6% 5% 26% 41% 17% 6%	198
March	1st to 10th	Day	17% 5% 30% 32% 14% 2	240
	11th to 20th	Day	15% 3 33% 30% 16% 3	240
	21st to end	Day	18% 7% 28% 28% 16% 2	446
April	1st to 10th	Day	13% 11% 38% 28% 9% 1	420
	11th to 20th	Day	19% 10% 30% 26% 13% 2	523
	21st to end	Day	17% 10% 27% 29% 15% 2	600
May	1st to 10th	Day	16% 8% 26% 32% 16% 2	603
	11th to 20th	Day	16% 7% 28% 27% 16% 7%	625
	21st to end	Day	17% 7% 26% 28% 16% 6%	679
June	1st to 10th	Day	18% 10% 28% 26% 13% 5%	630
	11th to 20th	Day	21% 9% 29% 25% 12% 5%	630
	21st to end	Day	16% 6% 25% 31% 16% 6%	630
July	1st to 10th	Day	11% 5% 21% 33% 23% 6%	621
	11th to 20th	Day	13% 7% 26% 28% 21% 6%	618
	21st to end	Day	10% 5% 23% 33% 19% 10%	684
August	1st to 10th	Day	11% 4 22% 35% 19% 9%	626
	11th to 20th	Day	12% 5% 22% 31% 20% 10%	615
	21st to end	Day	16% 6% 22% 33% 19% 3	621
September	1st to 10th	Day	14% 10% 32% 29% 14% 2	450
	11th to 20th	Day	21% 8% 24% 31% 11% 4	370
	21st to end	Day	19% 7% 31% 30% 10% 3	270
October	1st to 10th	Day	24% 7% 25% 26% 17% 1	270
	11th to 20th	Day	15% 9% 36% 27% 10% 4	270
	21st to end	Day	20% 6% 35% 26% 8% 4	297
November	1st to 10th	Day	27% 5% 30% 24% 10% 4	270
	11th to 20th	Day	15% 9% 37% 30% 8% 1	270
	21st to end	Day	19% 10% 31% 30% 10% 1	270
December	1st to 10th	Day	10% 6% 30% 36% 15% 4	270
	11th to 20th	Day	16% 9% 43% 24% 8% 1	270
	21st to end	Day	12% 3 30% 32% 19% 4	297
January	1st to 10th	Night	11% 8% 35% 32% 12% 1	950
	11th to 20th	Night	14% 9% 33% 34% 9% 1	950
	21st to end	Night	14% 9% 36% 30% 10% 1	1045
February	1st to 10th	Night	15% 6% 32% 31% 15% 1	950
	11th to 20th	Night	10% 6% 33% 36% 12% 3	806
	21st to end	Night	8% 5% 27% 37% 21% 3	592
March	1st to 10th	Night	15% 6% 28% 34% 15% 1	720
	11th to 20th	Night	11% 6% 32% 35% 13% 2	679
	21st to end	Night	14% 6% 29% 34% 14% 4	594
April	1st to 10th	Night	8% 8% 31% 36% 14% 2	540
	11th to 20th	Night	19% 8% 30% 32% 11% 1	533
	21st to end	Night	20% 5% 32% 33% 8% 1	540
May	1st to 10th	Night	16% 7% 26% 35% 14% 2	540
	11th to 20th	Night	17% 6% 28% 32% 16% 2	531
	21st to end	Night	21% 7% 25% 30% 15% 2	584
June	1st to 10th	Night	17% 6% 28% 34% 13% 2	540
	11th to 20th	Night	21% 4 26% 33% 15% 1	380
	21st to end	Night	13% 5% 26% 37% 19% 1	360
July	1st to 10th	Night	10% 4 23% 39% 23% 1	368
	11th to 20th	Night	11% 3 29% 39% 18% 2	522
	21st to end	Night	8% 3 22% 43% 20% 4	591
August	1st to 10th	Night	7% 4 21% 44% 22% 2	537
	11th to 20th	Night	11% 4 19% 35% 25% 5%	534
	21st to end	Night	14% 4 24% 38% 20% 1	594
September	1st to 10th	Night	12% 5% 26% 35% 19% 2	540
	11th to 20th	Night	16% 6% 26% 38% 13% 1	540
	21st to end	Night	12% 8% 30% 37% 12% 1	540
October	1st to 10th	Night	21% 5% 27% 33% 13% 1	648
	11th to 20th	Night	15% 7% 29% 35% 12% 2	862
	21st to end	Night	18% 8% 33% 31% 10% 1	990
November	1st to 10th	Night	20% 9% 30% 29% 10% 1	925
	11th to 20th	Night	17% 8% 36% 27% 10% 1	950
	21st to end	Night	15% 9% 38% 30% 7% 1	950
December	1st to 10th	Night	12% 6% 33% 32% 13% 4	950
	11th to 20th	Night	14% 10% 32% 31% 12% 1	950
	21st to end	Night	13% 5% 30% 36% 14% 3	1045

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