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 2026-07-31.

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% 9% 3 9% 5% 5% 5% 4 6% 8% 36%	143398
	Night	8% 9% 4 10% 6% 5% 5% 4 6% 7% 35%	138487
Transparency	Day	45% 4 15% 25% 9% 1	143109
	Night	47% 4 14% 24% 10% 1	138360
Seeing	Day	15% 8% 29% 29% 15% 4	18741
	Night	14% 7% 31% 34% 13% 2	28087

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	4 12% 7% 19% 7% 7% 6% 4 7% 8% 17%	4139
	11th to 20th	Day	4 10% 4 13% 10% 8% 9% 6% 9% 7% 18%	4716
	21st to end	Day	6% 10% 5% 11% 7% 5% 6% 5% 5% 8% 31%	5188
February	1st to 10th	Day	8% 13% 4 13% 9% 6% 7% 6% 6% 7% 21%	1680
	11th to 20th	Day	6% 11% 4 10% 8% 7% 7% 5% 6% 10% 27%	1812
	21st to end	Day	5% 11% 5% 11% 9% 8% 6% 5% 7% 7% 25%	1730
March	1st to 10th	Day	7% 12% 5% 15% 8% 6% 6% 3 6% 7% 24%	4600
	11th to 20th	Day	8% 13% 6% 16% 7% 6% 5% 4 5% 6% 25%	4760
	21st to end	Day	11% 12% 3 10% 6% 5% 4 4 7% 7% 31%	6070
April	1st to 10th	Day	8% 9% 4 9% 6% 6% 5% 4 5% 7% 38%	2520
	11th to 20th	Day	13% 14% 4 10% 6% 5% 4 3 6% 7% 28%	2625
	21st to end	Day	13% 8% 2 8% 6% 5% 6% 4 5% 7% 37%	2807
May	1st to 10th	Day	12% 8% 3 6% 4 4 4 3 5% 6% 44%	8224
	11th to 20th	Day	19% 8% 2 7% 5% 4 4 4 5% 8% 34%	8386
	21st to end	Day	10% 8% 2 7% 4 4 4 4 5% 7% 45%	9683
June	1st to 10th	Day	16% 8% 2 6% 4 4 5% 4 6% 8% 36%	3150
	11th to 20th	Day	18% 8% 3 8% 6% 5% 5% 5% 6% 8% 29%	3331
	21st to end	Day	15% 6% 2 6% 4 5% 5% 4 7% 8% 37%	3360
July	1st to 10th	Day	7% 4 2 6% 5% 5% 6% 5% 7% 9% 44%	7338
	11th to 20th	Day	10% 6% 2 6% 4 4 5% 4 7% 9% 44%	6816
	21st to end	Day	7% 4 1 5% 4 4 4 4 7% 9% 52%	7039
August	1st to 10th	Day	8% 5% 2 6% 5% 5% 6% 4 7% 10% 42%	4552
	11th to 20th	Day	8% 4 2 5% 4 4 5% 5% 7% 10% 46%	4451
	21st to end	Day	11% 5% 2 6% 4 4 4 4 5% 7% 48%	4543
September	1st to 10th	Day	10% 5% 2 5% 4 4 4 4 6% 7% 48%	2400
	11th to 20th	Day	13% 9% 3 7% 4 4 4 3 5% 7% 41%	2310
	21st to end	Day	11% 7% 2 6% 4 4 4 3 4 6% 49%	2200
October	1st to 10th	Day	12% 8% 2 6% 4 4 3 3 4 8% 45%	3385
	11th to 20th	Day	7% 9% 3 7% 4 3 4 4 6% 9% 46%	2956
	21st to end	Day	8% 12% 5% 9% 5% 4 6% 4 6% 6% 35%	3190
November	1st to 10th	Day	18% 15% 6% 9% 5% 4 4 3 3 5% 27%	1806
	11th to 20th	Day	10% 15% 7% 13% 7% 5% 5% 4 5% 6% 23%	1517
	21st to end	Day	10% 14% 6% 12% 7% 5% 5% 3 5% 5% 28%	1470
December	1st to 10th	Day	7% 13% 5% 17% 9% 8% 7% 5% 6% 6% 18%	2360
	11th to 20th	Day	7% 15% 6% 14% 7% 8% 5% 3 5% 9% 21%	2709
	21st to end	Day	4 9% 4 15% 7% 5% 5% 3 5% 6% 37%	3575
January	1st to 10th	Night	5% 12% 6% 18% 9% 7% 6% 4 5% 7% 21%	8781
	11th to 20th	Night	4 9% 4 15% 9% 8% 10% 7% 8% 8% 18%	8212
	21st to end	Night	4 9% 5% 13% 7% 6% 6% 5% 7% 8% 29%	9026
February	1st to 10th	Night	9% 13% 4 11% 8% 5% 6% 4 6% 7% 26%	2940
	11th to 20th	Night	5% 10% 3 10% 7% 6% 6% 6% 7% 7% 32%	2712
	21st to end	Night	5% 9% 5% 11% 7% 5% 6% 5% 5% 7% 35%	2076
March	1st to 10th	Night	7% 12% 6% 13% 6% 5% 5% 5% 6% 8% 27%	5494
	11th to 20th	Night	7% 11% 4 10% 7% 5% 5% 4 5% 8% 35%	5433
	21st to end	Night	8% 13% 4 9% 5% 5% 5% 4 6% 8% 33%	5122
April	1st to 10th	Night	5% 9% 3 8% 5% 5% 5% 3 7% 7% 42%	2100
	11th to 20th	Night	14% 11% 5% 8% 5% 5% 4 4 5% 6% 33%	1945
	21st to end	Night	13% 9% 3 8% 5% 5% 4 5% 6% 6% 36%	1811
May	1st to 10th	Night	10% 7% 2 6% 4 5% 4 4 6% 7% 46%	4724
	11th to 20th	Night	15% 7% 3 8% 5% 5% 6% 4 6% 8% 33%	4505
	21st to end	Night	11% 8% 2 6% 4 4 3 3 5% 7% 47%	4523
June	1st to 10th	Night	14% 7% 3 6% 5% 4 4 4 5% 7% 41%	1470
	11th to 20th	Night	18% 6% 2 5% 4 5% 4 4 6% 8% 38%	1283
	21st to end	Night	13% 6% 2 6% 5% 5% 5% 4 5% 8% 41%	1260
July	1st to 10th	Night	6% 4 1 5% 4 4 5% 4 8% 12% 46%	2842
	11th to 20th	Night	10% 4 2 4 3 3 4 3 6% 10% 52%	3380
	21st to end	Night	6% 3 1 3 3 2 3 3 6% 9% 61%	4048
August	1st to 10th	Night	6% 6% 2 5% 4 5% 4 4 6% 9% 49%	2608
	11th to 20th	Night	7% 4 1 5% 4 5% 5% 4 6% 7% 51%	2608
	21st to end	Night	9% 5% 2 5% 3 4 4 3 5% 8% 51%	3364
September	1st to 10th	Night	8% 5% 2 5% 3 4 5% 5% 6% 8% 49%	2000
	11th to 20th	Night	13% 8% 2 6% 4 3 4 4 6% 7% 44%	2090
	21st to end	Night	10% 6% 2 6% 3 3 5% 3 7% 7% 49%	2200
October	1st to 10th	Night	11% 8% 3 6% 3 4 4 3 4 7% 47%	3788
	11th to 20th	Night	6% 8% 3 6% 5% 5% 6% 5% 7% 10% 40%	4159
	21st to end	Night	9% 10% 4 8% 4 4 4 3 6% 6% 43%	4610
November	1st to 10th	Night	13% 15% 5% 9% 6% 5% 5% 4 4 6% 28%	2707
	11th to 20th	Night	9% 15% 5% 13% 8% 5% 5% 4 4 6% 26%	3103
	21st to end	Night	9% 12% 5% 12% 9% 5% 4 4 6% 7% 26%	3150
December	1st to 10th	Night	7% 16% 6% 15% 9% 9% 7% 4 5% 5% 17%	5050
	11th to 20th	Night	7% 14% 6% 12% 6% 7% 6% 5% 6% 8% 24%	5718
	21st to end	Night	5% 8% 4 15% 8% 6% 5% 3 4 5% 37%	7645

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% 3 13% 12% 8%	4139
	11th to 20th	Day	59% 3 11% 19% 8%	4740
	21st to end	Day	51% 3 17% 21% 8%	5188
February	1st to 10th	Day	60% 4 14% 14% 7%	1680
	11th to 20th	Day	51% 4 10% 23% 12%	1820
	21st to end	Day	55% 4 11% 20% 10%	1730
March	1st to 10th	Day	58% 5% 14% 16% 7%	4600
	11th to 20th	Day	60% 4 12% 19% 5%	4761
	21st to end	Day	50% 3 10% 23% 13%	6070
April	1st to 10th	Day	45% 4 16% 24% 11% 1	2520
	11th to 20th	Day	55% 4 13% 18% 8% 2	2625
	21st to end	Day	45% 5% 16% 24% 9% 1	2807
May	1st to 10th	Day	41% 3 11% 28% 16%	8224
	11th to 20th	Day	49% 4 11% 24% 10% 1	8390
	21st to end	Day	38% 4 10% 27% 21% 1	9683
June	1st to 10th	Day	45% 4 14% 26% 10% 1	3150
	11th to 20th	Day	51% 6% 14% 19% 9% 1	3331
	21st to end	Day	43% 5% 19% 26% 7%	3360
July	1st to 10th	Day	33% 7% 26% 29% 5%	7260
	11th to 20th	Day	35% 6% 17% 37% 4	6735
	21st to end	Day	28% 5% 23% 34% 9% 1	6846
August	1st to 10th	Day	36% 6% 20% 29% 9%	4536
	11th to 20th	Day	30% 6% 23% 35% 6%	4493
	21st to end	Day	35% 5% 19% 35% 6%	4542
September	1st to 10th	Day	34% 4 18% 32% 11% 1	2400
	11th to 20th	Day	43% 4 16% 27% 8% 1	2310
	21st to end	Day	38% 3 12% 33% 13% 1	2200
October	1st to 10th	Day	40% 3 18% 31% 7% 1	3385
	11th to 20th	Day	36% 3 18% 35% 7%	2956
	21st to end	Day	49% 4 16% 24% 7%	3190
November	1st to 10th	Day	60% 4 11% 17% 6% 1	1806
	11th to 20th	Day	62% 4 14% 13% 7%	1517
	21st to end	Day	57% 5% 13% 20% 4	1470
December	1st to 10th	Day	66% 7% 11% 13% 4	2360
	11th to 20th	Day	62% 3 16% 15% 3	2710
	21st to end	Day	49% 3 10% 22% 12% 4	3575
January	1st to 10th	Night	63% 3 10% 17% 7%	8782
	11th to 20th	Night	60% 4 13% 16% 6%	8250
	21st to end	Night	51% 6% 17% 18% 8%	9026
February	1st to 10th	Night	56% 4 12% 18% 9% 1	2940
	11th to 20th	Night	47% 4 13% 24% 11%	2714
	21st to end	Night	48% 3 13% 27% 9%	2076
March	1st to 10th	Night	54% 4 17% 19% 6%	5494
	11th to 20th	Night	46% 4 13% 25% 11%	5433
	21st to end	Night	48% 3 9% 27% 12% 1	5122
April	1st to 10th	Night	40% 3 13% 26% 17% 1	2100
	11th to 20th	Night	50% 4 10% 23% 12% 1	1945
	21st to end	Night	46% 5% 12% 25% 12% 1	1811
May	1st to 10th	Night	37% 4 12% 29% 17% 1	4724
	11th to 20th	Night	48% 5% 13% 24% 10% 1	4505
	21st to end	Night	36% 4 10% 26% 23% 2	4526
June	1st to 10th	Night	42% 4 14% 25% 13% 2	1470
	11th to 20th	Night	44% 5% 18% 19% 13% 2	1283
	21st to end	Night	41% 6% 20% 25% 7% 1	1260
July	1st to 10th	Night	29% 6% 27% 32% 6%	2811
	11th to 20th	Night	28% 5% 18% 42% 6%	3338
	21st to end	Night	22% 5% 25% 34% 14% 1	3936
August	1st to 10th	Night	30% 7% 22% 30% 11%	2600
	11th to 20th	Night	30% 5% 20% 36% 8%	2632
	21st to end	Night	32% 5% 18% 36% 9%	3364
September	1st to 10th	Night	31% 6% 14% 34% 13% 2	2000
	11th to 20th	Night	39% 4 17% 28% 10% 1	2090
	21st to end	Night	33% 4 14% 33% 14% 2	2200
October	1st to 10th	Night	39% 2 16% 31% 10% 2	3788
	11th to 20th	Night	38% 4 14% 33% 11% 1	4159
	21st to end	Night	41% 4 15% 31% 9%	4610
November	1st to 10th	Night	57% 3 14% 17% 7% 1	2707
	11th to 20th	Night	60% 4 16% 14% 5%	3103
	21st to end	Night	57% 4 17% 18% 5%	3150
December	1st to 10th	Night	69% 4 10% 13% 4	5050
	11th to 20th	Night	57% 4 13% 20% 5%	5716
	21st to end	Night	50% 3 10% 21% 13% 4	7645

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	12% 6% 34% 28% 17% 2	330
	11th to 20th	Day	10% 7% 37% 34% 12% 1	330
	21st to end	Day	15% 7% 30% 31% 13% 2	363
February	1st to 10th	Day	13% 8% 35% 31% 12% 1	330
	11th to 20th	Day	8% 5% 32% 30% 20% 4	330
	21st to end	Day	6% 8% 28% 40% 14% 4	273
March	1st to 10th	Day	15% 8% 32% 30% 13% 2	330
	11th to 20th	Day	15% 6% 32% 29% 15% 3	330
	21st to end	Day	18% 7% 29% 29% 15% 3	576
April	1st to 10th	Day	12% 11% 37% 29% 10% 2	540
	11th to 20th	Day	20% 12% 31% 25% 10% 1	663
	21st to end	Day	16% 9% 29% 29% 15% 3	750
May	1st to 10th	Day	16% 8% 28% 31% 15% 2	753
	11th to 20th	Day	19% 8% 28% 26% 14% 6%	775
	21st to end	Day	16% 7% 26% 29% 17% 6%	844
June	1st to 10th	Day	19% 12% 29% 25% 11% 4	780
	11th to 20th	Day	19% 10% 29% 26% 12% 4	780
	21st to end	Day	18% 7% 24% 30% 15% 5%	780
July	1st to 10th	Day	11% 5% 22% 32% 22% 8%	771
	11th to 20th	Day	13% 6% 26% 28% 20% 7%	768
	21st to end	Day	9% 5% 24% 34% 19% 9%	845
August	1st to 10th	Day	11% 5% 23% 34% 19% 8%	726
	11th to 20th	Day	11% 5% 24% 31% 20% 10%	715
	21st to end	Day	15% 7% 22% 32% 20% 3	723
September	1st to 10th	Day	13% 10% 31% 28% 16% 3	530
	11th to 20th	Day	20% 10% 25% 31% 10% 4	440
	21st to end	Day	17% 8% 32% 29% 12% 2	330
October	1st to 10th	Day	22% 9% 26% 25% 17% 1	330
	11th to 20th	Day	17% 10% 35% 25% 10% 3	330
	21st to end	Day	19% 7% 36% 27% 8% 3	363
November	1st to 10th	Day	25% 8% 29% 25% 10% 3	330
	11th to 20th	Day	17% 10% 37% 28% 7% 1	330
	21st to end	Day	15% 9% 33% 32% 10% 1	330
December	1st to 10th	Day	11% 6% 34% 33% 13% 3	330
	11th to 20th	Day	15% 9% 42% 26% 7% 1	330
	21st to end	Day	14% 3 31% 31% 17% 4	363
January	1st to 10th	Night	11% 8% 36% 32% 12% 1	1050
	11th to 20th	Night	14% 10% 35% 32% 8% 1	1050
	21st to end	Night	13% 10% 38% 29% 10% 1	1155
February	1st to 10th	Night	15% 8% 32% 30% 14% 1	1050
	11th to 20th	Night	10% 6% 32% 37% 13% 3	916
	21st to end	Night	8% 6% 29% 36% 18% 2	692
March	1st to 10th	Night	15% 8% 30% 33% 14% 1	840
	11th to 20th	Night	11% 6% 33% 36% 12% 2	791
	21st to end	Night	15% 5% 30% 34% 12% 3	693
April	1st to 10th	Night	9% 7% 31% 37% 14% 2	630
	11th to 20th	Night	19% 8% 31% 32% 9%	623
	21st to end	Night	19% 5% 33% 34% 9% 1	630
May	1st to 10th	Night	16% 7% 27% 34% 14% 1	630
	11th to 20th	Night	17% 6% 30% 31% 14% 1	621
	21st to end	Night	20% 6% 26% 33% 14% 1	683
June	1st to 10th	Night	18% 7% 29% 33% 12% 1	630
	11th to 20th	Night	21% 4 27% 35% 13% 1	443
	21st to end	Night	14% 5% 25% 36% 18% 1	420
July	1st to 10th	Night	10% 5% 22% 37% 25% 1	432
	11th to 20th	Night	11% 4 28% 38% 17% 1	612
	21st to end	Night	8% 3 22% 44% 19% 4	687
August	1st to 10th	Night	8% 4 20% 45% 21% 2	597
	11th to 20th	Night	11% 4 20% 35% 25% 5%	594
	21st to end	Night	13% 4 25% 38% 19% 1	660
September	1st to 10th	Night	12% 5% 26% 36% 19% 2	600
	11th to 20th	Night	17% 7% 25% 37% 13% 1	600
	21st to end	Night	11% 8% 30% 39% 11% 1	600
October	1st to 10th	Night	20% 5% 27% 34% 12% 1	720
	11th to 20th	Night	15% 8% 30% 34% 11% 2	958
	21st to end	Night	17% 8% 34% 31% 9% 1	1100
November	1st to 10th	Night	19% 9% 32% 29% 10% 1	1025
	11th to 20th	Night	17% 9% 37% 26% 10% 1	1050
	21st to end	Night	15% 9% 37% 31% 8% 1	1050
December	1st to 10th	Night	12% 6% 34% 32% 13% 4	1050
	11th to 20th	Night	14% 11% 32% 30% 11% 1	1050
	21st to end	Night	13% 5% 30% 36% 14% 3	1155

Page generated at 2026-07-28 01:25:26. Version ac07

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