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 2025-03-27.

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% 6% 5% 5% 4 6% 8% 36%	113180
	Night	8% 9% 4 10% 6% 5% 5% 4 6% 7% 35%	114891
Transparency	Day	46% 4 16% 26% 8% 1	112933
	Night	47% 4 15% 24% 9% 1	114784
Seeing	Day	15% 7% 28% 30% 15% 4	16721
	Night	14% 7% 30% 34% 13% 2	26382

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	5% 14% 7% 19% 8% 7% 6% 4 7% 8% 16%	3193
	11th to 20th	Day	4 8% 4 12% 11% 8% 8% 7% 11% 8% 18%	3616
	21st to end	Day	7% 12% 6% 14% 8% 4 5% 5% 5% 6% 28%	4004
February	1st to 10th	Day	8% 13% 4 12% 9% 6% 7% 6% 6% 8% 22%	1600
	11th to 20th	Day	6% 11% 4 10% 7% 7% 7% 5% 6% 9% 28%	1723
	21st to end	Day	5% 11% 5% 11% 10% 7% 6% 5% 7% 7% 25%	1650
March	1st to 10th	Day	9% 13% 5% 12% 7% 6% 6% 4 6% 7% 24%	3230
	11th to 20th	Day	7% 12% 5% 14% 7% 6% 5% 4 5% 6% 28%	3352
	21st to end	Day	8% 10% 3 9% 6% 6% 5% 4 7% 8% 35%	4221
April	1st to 10th	Day	8% 9% 4 9% 6% 6% 4 4 5% 8% 38%	2280
	11th to 20th	Day	14% 15% 4 10% 7% 5% 3 3 6% 6% 28%	2372
	21st to end	Day	13% 8% 2 7% 5% 5% 6% 4 6% 7% 38%	2539
May	1st to 10th	Day	19% 9% 3 6% 5% 4 4 3 4 6% 37%	4430
	11th to 20th	Day	14% 8% 3 8% 6% 5% 4 4 5% 7% 36%	4499
	21st to end	Day	14% 10% 3 8% 5% 5% 5% 4 5% 7% 34%	5173
June	1st to 10th	Day	17% 7% 2 6% 4 4 5% 4 6% 8% 37%	2850
	11th to 20th	Day	19% 8% 3 7% 6% 5% 4 5% 6% 8% 29%	3013
	21st to end	Day	14% 6% 2 6% 4 5% 5% 4 7% 8% 38%	3040
July	1st to 10th	Day	8% 4 2 6% 5% 5% 6% 5% 8% 9% 42%	5012
	11th to 20th	Day	7% 5% 1 4 4 4 4 3 6% 9% 52%	4661
	21st to end	Day	5% 4 1 4 4 4 4 4 7% 9% 54%	4802
August	1st to 10th	Day	8% 5% 2 6% 4 5% 6% 4 7% 10% 43%	4412
	11th to 20th	Day	8% 4 2 5% 4 4 5% 5% 7% 10% 47%	4312
	21st to end	Day	12% 6% 2 6% 4 4 4 3 5% 7% 48%	4404
September	1st to 10th	Day	11% 5% 2 5% 4 4 4 4 6% 7% 48%	2280
	11th to 20th	Day	13% 8% 3 7% 4 4 4 3 5% 7% 42%	2195
	21st to end	Day	12% 7% 2 7% 4 4 4 3 4 6% 47%	2090
October	1st to 10th	Day	13% 8% 2 6% 4 4 3 3 4 8% 45%	3281
	11th to 20th	Day	7% 8% 2 7% 4 3 3 4 7% 9% 47%	2865
	21st to end	Day	8% 12% 5% 9% 5% 4 6% 4 6% 6% 35%	3091
November	1st to 10th	Day	18% 16% 7% 9% 5% 4 4 3 3 5% 26%	1718
	11th to 20th	Day	10% 16% 7% 14% 7% 5% 5% 4 5% 6% 22%	1445
	21st to end	Day	10% 15% 6% 12% 8% 5% 5% 3 4 5% 27%	1400
December	1st to 10th	Day	7% 13% 4 17% 9% 8% 7% 5% 6% 6% 17%	2290
	11th to 20th	Day	7% 15% 6% 14% 8% 8% 5% 3 4 9% 21%	2639
	21st to end	Day	4 8% 4 15% 7% 5% 5% 3 5% 6% 37%	3498
January	1st to 10th	Night	4 12% 6% 19% 9% 7% 6% 4 5% 7% 20%	6769
	11th to 20th	Night	4 9% 4 15% 9% 8% 9% 7% 8% 9% 17%	6302
	21st to end	Night	5% 12% 7% 15% 7% 6% 5% 4 6% 7% 26%	6974
February	1st to 10th	Night	9% 13% 4 10% 8% 6% 6% 5% 7% 7% 26%	2800
	11th to 20th	Night	4 10% 3 10% 7% 6% 6% 6% 7% 8% 32%	2580
	21st to end	Night	5% 9% 5% 11% 7% 5% 6% 5% 5% 7% 36%	1980
March	1st to 10th	Night	8% 12% 5% 10% 6% 5% 5% 4 6% 8% 30%	3854
	11th to 20th	Night	7% 10% 3 8% 6% 5% 4 4 5% 8% 39%	3834
	21st to end	Night	6% 9% 3 8% 6% 5% 5% 4 7% 9% 39%	3557
April	1st to 10th	Night	5% 9% 3 8% 5% 5% 5% 3 6% 7% 43%	1900
	11th to 20th	Night	15% 11% 4 8% 4 5% 4 4 6% 6% 33%	1758
	21st to end	Night	14% 8% 3 7% 6% 5% 4 5% 7% 6% 35%	1639
May	1st to 10th	Night	17% 10% 3 6% 4 4 4 4 6% 6% 36%	2540
	11th to 20th	Night	11% 6% 3 8% 5% 5% 6% 4 6% 8% 37%	2405
	21st to end	Night	13% 9% 3 7% 4 5% 4 5% 6% 8% 38%	2414
June	1st to 10th	Night	14% 7% 2 5% 5% 5% 4 3 6% 7% 43%	1330
	11th to 20th	Night	18% 6% 2 6% 4 5% 4 4 6% 8% 38%	1161
	21st to end	Night	11% 6% 2 6% 5% 5% 5% 4 5% 8% 43%	1140
July	1st to 10th	Night	7% 4 1 6% 5% 5% 5% 4 9% 13% 40%	1947
	11th to 20th	Night	6% 3 1 4 3 3 3 3 5% 8% 60%	2306
	21st to end	Night	3 3 1 3 2 2 3 3 6% 10% 63%	2762
August	1st to 10th	Night	6% 5% 2 5% 4 5% 4 4 6% 9% 49%	2528
	11th to 20th	Night	7% 4 1 5% 4 5% 5% 4 7% 7% 51%	2527
	21st to end	Night	9% 5% 2 5% 3 4 4 3 5% 8% 51%	3261
September	1st to 10th	Night	8% 5% 2 5% 3 4 5% 5% 6% 8% 50%	1900
	11th to 20th	Night	13% 8% 2 5% 4 3 4 4 6% 7% 46%	1985
	21st to end	Night	10% 6% 2 6% 3 3 5% 3 7% 8% 47%	2090
October	1st to 10th	Night	12% 9% 3 6% 3 4 4 3 4 7% 46%	3672
	11th to 20th	Night	6% 8% 2 6% 5% 5% 6% 5% 7% 10% 40%	4031
	21st to end	Night	9% 9% 4 8% 4 4 4 3 6% 7% 43%	4467
November	1st to 10th	Night	13% 15% 5% 9% 7% 5% 4 4 4 6% 28%	2575
	11th to 20th	Night	9% 16% 5% 13% 9% 5% 5% 4 4 6% 25%	2955
	21st to end	Night	9% 12% 5% 12% 9% 5% 4 4 6% 7% 26%	3000
December	1st to 10th	Night	7% 16% 6% 15% 9% 9% 7% 4 5% 5% 17%	4900
	11th to 20th	Night	7% 14% 6% 12% 6% 7% 6% 5% 6% 8% 23%	5568
	21st to end	Night	5% 7% 4 15% 8% 6% 5% 3 4 5% 38%	7480

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 12% 14% 6%	3193
	11th to 20th	Day	56% 3 12% 21% 7%	3640
	21st to end	Day	58% 4 14% 20% 4	4004
February	1st to 10th	Day	59% 4 14% 15% 7%	1600
	11th to 20th	Day	50% 4 10% 24% 11%	1731
	21st to end	Day	55% 4 11% 20% 11%	1650
March	1st to 10th	Day	57% 4 13% 20% 6%	3230
	11th to 20th	Day	56% 4 15% 20% 4	3353
	21st to end	Day	45% 3 11% 24% 15% 1	4221
April	1st to 10th	Day	45% 4 15% 25% 11% 1	2280
	11th to 20th	Day	55% 4 12% 19% 8% 2	2372
	21st to end	Day	44% 5% 17% 24% 9%	2539
May	1st to 10th	Day	48% 4 12% 26% 9%	4430
	11th to 20th	Day	47% 5% 11% 23% 13% 2	4503
	21st to end	Day	48% 4 12% 27% 7%	5173
June	1st to 10th	Day	44% 4 15% 26% 9% 1	2850
	11th to 20th	Day	51% 6% 14% 19% 9% 1	3013
	21st to end	Day	42% 5% 19% 26% 7%	3040
July	1st to 10th	Day	33% 8% 26% 29% 4	4934
	11th to 20th	Day	29% 5% 18% 42% 6%	4580
	21st to end	Day	25% 5% 23% 36% 10% 1	4651
August	1st to 10th	Day	35% 6% 20% 29% 9%	4396
	11th to 20th	Day	30% 6% 23% 36% 6%	4354
	21st to end	Day	35% 5% 19% 35% 6%	4403
September	1st to 10th	Day	34% 4 18% 31% 12% 1	2280
	11th to 20th	Day	42% 4 17% 28% 9% 1	2195
	21st to end	Day	40% 3 12% 32% 12% 1	2090
October	1st to 10th	Day	41% 3 18% 31% 7%	3281
	11th to 20th	Day	35% 3 18% 36% 7%	2865
	21st to end	Day	49% 4 16% 23% 7%	3091
November	1st to 10th	Day	61% 4 11% 17% 7%	1718
	11th to 20th	Day	63% 4 14% 13% 6%	1445
	21st to end	Day	59% 5% 13% 19% 4	1400
December	1st to 10th	Day	66% 7% 11% 12% 4	2290
	11th to 20th	Day	62% 3 17% 15% 2	2640
	21st to end	Day	49% 3 11% 22% 12% 4	3498
January	1st to 10th	Night	63% 3 11% 18% 4	6769
	11th to 20th	Night	60% 4 14% 15% 6%	6340
	21st to end	Night	56% 6% 17% 17% 4	6974
February	1st to 10th	Night	55% 4 12% 18% 10% 1	2800
	11th to 20th	Night	47% 5% 14% 23% 11%	2582
	21st to end	Night	47% 3 13% 27% 10%	1980
March	1st to 10th	Night	52% 3 17% 21% 6%	3854
	11th to 20th	Night	42% 4 15% 27% 10% 1	3834
	21st to end	Night	41% 4 10% 30% 14% 1	3557
April	1st to 10th	Night	39% 3 13% 26% 18% 1	1900
	11th to 20th	Night	51% 4 9% 23% 12% 2	1758
	21st to end	Night	46% 5% 12% 24% 12% 1	1639
May	1st to 10th	Night	47% 5% 14% 21% 13% 1	2540
	11th to 20th	Night	44% 5% 12% 23% 15% 1	2405
	21st to end	Night	43% 5% 13% 29% 9% 1	2414
June	1st to 10th	Night	41% 5% 15% 25% 13% 2	1330
	11th to 20th	Night	43% 5% 18% 18% 14% 2	1161
	21st to end	Night	39% 5% 20% 27% 8% 1	1140
July	1st to 10th	Night	33% 7% 28% 26% 6%	1916
	11th to 20th	Night	23% 4 18% 46% 9%	2264
	21st to end	Night	18% 4 25% 37% 15% 1	2674
August	1st to 10th	Night	30% 7% 22% 30% 11%	2520
	11th to 20th	Night	30% 5% 20% 36% 9%	2551
	21st to end	Night	33% 5% 18% 35% 9%	3261
September	1st to 10th	Night	31% 5% 14% 33% 14% 3	1900
	11th to 20th	Night	38% 4 17% 30% 11% 1	1985
	21st to end	Night	35% 4 13% 32% 14% 2	2090
October	1st to 10th	Night	40% 2 16% 30% 10% 2	3672
	11th to 20th	Night	37% 4 14% 33% 10% 1	4031
	21st to end	Night	41% 4 15% 31% 9%	4467
November	1st to 10th	Night	58% 3 15% 17% 7% 1	2575
	11th to 20th	Night	61% 4 16% 14% 4	2955
	21st to end	Night	57% 4 17% 17% 5%	3000
December	1st to 10th	Night	69% 4 10% 12% 4	4900
	11th to 20th	Night	57% 4 13% 20% 5%	5566
	21st to end	Night	50% 3 9% 21% 14% 4	7480

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	13% 7% 33% 27% 17% 3	300
	11th to 20th	Day	8% 6% 36% 37% 12% 1	300
	21st to end	Day	16% 7% 29% 33% 13% 2	330
February	1st to 10th	Day	14% 7% 34% 32% 12% 1	300
	11th to 20th	Day	8% 5% 33% 31% 19% 4	300
	21st to end	Day	6% 7% 28% 41% 14% 5%	249
March	1st to 10th	Day	15% 7% 30% 31% 14% 3	300
	11th to 20th	Day	15% 6% 32% 28% 15% 3	300
	21st to end	Day	17% 7% 28% 30% 16% 3	514
April	1st to 10th	Day	12% 10% 38% 28% 10% 1	460
	11th to 20th	Day	21% 10% 31% 24% 12% 2	570
	21st to end	Day	16% 9% 28% 30% 14% 2	650
May	1st to 10th	Day	17% 8% 27% 31% 15% 2	653
	11th to 20th	Day	16% 7% 29% 27% 15% 6%	675
	21st to end	Day	16% 7% 26% 28% 16% 6%	734
June	1st to 10th	Day	19% 11% 29% 26% 12% 5%	680
	11th to 20th	Day	20% 10% 29% 25% 12% 4	680
	21st to end	Day	16% 7% 24% 31% 16% 5%	680
July	1st to 10th	Day	11% 5% 21% 33% 23% 8%	671
	11th to 20th	Day	12% 6% 25% 28% 21% 8%	668
	21st to end	Day	9% 6% 23% 32% 20% 10%	739
August	1st to 10th	Day	11% 4 22% 35% 18% 9%	676
	11th to 20th	Day	11% 5% 21% 31% 21% 10%	665
	21st to end	Day	15% 7% 23% 33% 19% 3	672
September	1st to 10th	Day	13% 10% 32% 28% 15% 2	490
	11th to 20th	Day	20% 10% 25% 31% 10% 4	405
	21st to end	Day	18% 9% 31% 29% 10% 2	300
October	1st to 10th	Day	23% 8% 27% 25% 17% 1	300
	11th to 20th	Day	15% 10% 36% 26% 10% 3	300
	21st to end	Day	19% 7% 36% 26% 8% 4	330
November	1st to 10th	Day	26% 7% 30% 25% 9% 3	300
	11th to 20th	Day	17% 9% 37% 28% 7% 1	300
	21st to end	Day	17% 10% 32% 30% 10% 1	300
December	1st to 10th	Day	10% 7% 33% 34% 14% 3	300
	11th to 20th	Day	15% 8% 41% 27% 8% 1	300
	21st to end	Day	12% 2 29% 33% 19% 4	330
January	1st to 10th	Night	11% 8% 35% 32% 12% 2	1000
	11th to 20th	Night	14% 9% 34% 33% 8% 1	1000
	21st to end	Night	14% 9% 38% 29% 10% 1	1100
February	1st to 10th	Night	15% 7% 33% 30% 15% 1	1000
	11th to 20th	Night	10% 6% 32% 37% 12% 3	872
	21st to end	Night	8% 6% 28% 37% 19% 2	660
March	1st to 10th	Night	14% 7% 30% 34% 15% 1	800
	11th to 20th	Night	10% 6% 33% 36% 13% 2	753
	21st to end	Night	14% 5% 29% 35% 13% 4	647
April	1st to 10th	Night	8% 8% 31% 36% 14% 2	570
	11th to 20th	Night	20% 8% 30% 31% 10% 1	563
	21st to end	Night	19% 5% 34% 34% 8% 1	570
May	1st to 10th	Night	17% 7% 26% 34% 14% 2	570
	11th to 20th	Night	17% 6% 29% 32% 15% 1	561
	21st to end	Night	20% 7% 25% 32% 15% 2	617
June	1st to 10th	Night	17% 6% 27% 35% 13% 2	570
	11th to 20th	Night	21% 4 27% 33% 14% 1	401
	21st to end	Night	13% 6% 25% 37% 18% 1	380
July	1st to 10th	Night	9% 4 23% 37% 25% 1	390
	11th to 20th	Night	10% 3 28% 38% 19% 2	552
	21st to end	Night	8% 3 22% 43% 20% 4	624
August	1st to 10th	Night	7% 4 21% 44% 21% 2	567
	11th to 20th	Night	11% 4 19% 35% 26% 5%	564
	21st to end	Night	13% 4 26% 37% 19% 1	627
September	1st to 10th	Night	12% 5% 26% 36% 19% 2	570
	11th to 20th	Night	16% 6% 26% 38% 13% 1	570
	21st to end	Night	12% 8% 31% 37% 11% 1	570
October	1st to 10th	Night	21% 6% 27% 33% 12% 1	684
	11th to 20th	Night	14% 7% 30% 35% 11% 2	910
	21st to end	Night	17% 8% 34% 31% 9% 1	1045
November	1st to 10th	Night	19% 9% 31% 30% 10% 1	975
	11th to 20th	Night	18% 9% 37% 27% 10% 1	1000
	21st to end	Night	15% 9% 38% 30% 7% 1	1000
December	1st to 10th	Night	12% 6% 34% 32% 13% 4	1000
	11th to 20th	Night	14% 10% 32% 31% 12% 1	1000
	21st to end	Night	13% 5% 29% 36% 15% 3	1100

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