Wetaskiwin
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wetaskiwin clear sky chart from 2005-11-06 to 2025-04-26.

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% 9% 3 8% 6% 5% 5% 4 6% 8% 36%	117091
	Night	8% 10% 4 10% 6% 5% 5% 4 6% 8% 33%	120229
Transparency	Day	43% 9% 17% 22% 8% 1	116834
	Night	46% 8% 16% 20% 9% 1	120132
Seeing	Day	12% 7% 25% 31% 19% 6%	15943
	Night	12% 6% 29% 35% 15% 2	25169

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% 4 11% 9% 7% 6% 4 6% 7% 30%	3179
	11th to 20th	Day	3 9% 4 10% 8% 7% 6% 5% 8% 10% 29%	3159
	21st to end	Day	6% 12% 4 9% 5% 5% 6% 4 6% 8% 35%	3800
February	1st to 10th	Day	6% 14% 5% 12% 7% 6% 5% 4 7% 8% 27%	1600
	11th to 20th	Day	6% 13% 4 12% 9% 5% 6% 5% 7% 7% 27%	1716
	21st to end	Day	4 11% 6% 10% 7% 8% 8% 6% 7% 8% 25%	1544
March	1st to 10th	Day	3 9% 5% 11% 8% 6% 6% 4 6% 9% 34%	4518
	11th to 20th	Day	6% 11% 4 11% 6% 4 4 4 5% 8% 36%	4971
	21st to end	Day	10% 16% 6% 14% 5% 4 4 4 5% 7% 24%	5544
April	1st to 10th	Day	9% 11% 4 10% 7% 5% 5% 4 6% 8% 31%	2498
	11th to 20th	Day	12% 12% 4 8% 6% 5% 6% 4 6% 8% 30%	2570
	21st to end	Day	13% 9% 3 7% 6% 6% 5% 5% 6% 9% 32%	2537
May	1st to 10th	Day	16% 11% 4 9% 5% 5% 4 4 5% 6% 30%	4580
	11th to 20th	Day	12% 10% 3 8% 6% 6% 6% 4 7% 8% 30%	4694
	21st to end	Day	14% 8% 3 9% 6% 6% 6% 5% 6% 7% 30%	5161
June	1st to 10th	Day	16% 7% 3 8% 5% 4 5% 4 6% 9% 31%	2850
	11th to 20th	Day	18% 10% 3 9% 6% 6% 5% 4 7% 7% 25%	2850
	21st to end	Day	11% 5% 2 6% 5% 4 6% 5% 7% 10% 38%	2850
July	1st to 10th	Day	8% 5% 2 5% 4 4 4 4 6% 8% 52%	4740
	11th to 20th	Day	9% 4 2 5% 4 4 4 4 7% 8% 48%	4740
	21st to end	Day	10% 5% 2 5% 4 4 4 4 5% 9% 47%	5138
August	1st to 10th	Day	11% 5% 2 6% 5% 4 5% 5% 6% 8% 43%	4480
	11th to 20th	Day	8% 5% 2 5% 5% 4 5% 5% 8% 11% 42%	4120
	21st to end	Day	10% 5% 2 6% 4 5% 5% 4 7% 9% 44%	4521
September	1st to 10th	Day	12% 5% 2 6% 4 4 5% 4 6% 8% 44%	2405
	11th to 20th	Day	15% 8% 2 6% 4 3 4 3 5% 8% 42%	2090
	21st to end	Day	9% 6% 2 6% 4 5% 5% 4 6% 8% 44%	2090
October	1st to 10th	Day	8% 9% 3 8% 4 5% 5% 3 5% 7% 42%	3298
	11th to 20th	Day	8% 8% 4 7% 5% 5% 5% 4 7% 9% 38%	2909
	21st to end	Day	7% 10% 3 8% 5% 5% 6% 4 5% 6% 40%	3075
November	1st to 10th	Day	9% 15% 5% 9% 6% 6% 6% 4 6% 6% 27%	1568
	11th to 20th	Day	6% 12% 5% 13% 6% 5% 5% 4 6% 7% 30%	1466
	21st to end	Day	5% 11% 6% 14% 7% 5% 5% 5% 6% 7% 29%	1400
December	1st to 10th	Day	11% 15% 6% 11% 6% 6% 6% 4 6% 7% 23%	2290
	11th to 20th	Day	6% 14% 5% 12% 7% 7% 7% 5% 7% 8% 23%	2642
	21st to end	Day	3 7% 3 10% 6% 5% 5% 3 5% 8% 45%	3498
January	1st to 10th	Night	4 10% 5% 15% 10% 8% 6% 4 6% 7% 26%	6766
	11th to 20th	Night	3 9% 4 11% 8% 6% 5% 5% 6% 6% 35%	6739
	21st to end	Night	6% 12% 4 10% 6% 5% 5% 4 6% 8% 34%	7200
February	1st to 10th	Night	5% 11% 5% 13% 8% 7% 7% 5% 6% 6% 28%	2800
	11th to 20th	Night	5% 13% 5% 11% 6% 6% 6% 5% 7% 7% 29%	2570
	21st to end	Night	5% 11% 3 11% 7% 5% 6% 6% 7% 7% 32%	2085
March	1st to 10th	Night	3 10% 5% 11% 7% 5% 6% 5% 8% 11% 30%	5376
	11th to 20th	Night	5% 10% 4 11% 7% 6% 6% 6% 7% 9% 29%	5027
	21st to end	Night	10% 15% 6% 15% 5% 5% 5% 4 6% 6% 22%	5429
April	1st to 10th	Night	7% 11% 3 9% 6% 7% 5% 4 7% 8% 32%	1901
	11th to 20th	Night	10% 13% 4 10% 5% 5% 6% 4 7% 8% 26%	1781
	21st to end	Night	13% 9% 3 7% 5% 4 6% 5% 6% 8% 33%	1759
May	1st to 10th	Night	23% 11% 4 7% 5% 4 5% 4 5% 5% 27%	2376
	11th to 20th	Night	11% 10% 3 9% 7% 6% 7% 5% 7% 9% 27%	2199
	21st to end	Night	15% 9% 3 10% 6% 6% 6% 5% 7% 9% 25%	2414
June	1st to 10th	Night	16% 8% 3 8% 5% 5% 5% 6% 7% 6% 30%	1330
	11th to 20th	Night	16% 11% 4 9% 8% 5% 6% 5% 7% 9% 21%	1330
	21st to end	Night	11% 5% 3 7% 4 5% 6% 7% 8% 9% 36%	1330
July	1st to 10th	Night	9% 5% 2 7% 5% 4 4 4 7% 8% 44%	2220
	11th to 20th	Night	7% 5% 2 6% 6% 5% 5% 4 7% 11% 41%	2220
	21st to end	Night	12% 5% 1 5% 4 3 5% 4 6% 9% 44%	2414
August	1st to 10th	Night	13% 5% 2 6% 4 3 5% 4 7% 9% 41%	2447
	11th to 20th	Night	9% 6% 3 7% 5% 5% 5% 5% 7% 9% 39%	2715
	21st to end	Night	10% 5% 2 7% 5% 4 5% 5% 7% 9% 42%	3146
September	1st to 10th	Night	12% 5% 3 6% 5% 4 5% 4 6% 8% 43%	1772
	11th to 20th	Night	14% 7% 2 5% 4 4 4 3 5% 7% 44%	2090
	21st to end	Night	9% 6% 3 7% 4 4 5% 3 7% 7% 44%	2090
October	1st to 10th	Night	9% 7% 3 7% 4 4 5% 4 6% 8% 42%	3676
	11th to 20th	Night	8% 9% 3 7% 5% 5% 5% 4 6% 9% 40%	4017
	21st to end	Night	5% 10% 3 9% 6% 5% 5% 5% 6% 8% 36%	4457
November	1st to 10th	Night	11% 15% 5% 9% 6% 4 4 4 5% 6% 29%	2725
	11th to 20th	Night	6% 13% 5% 12% 6% 6% 5% 4 6% 8% 28%	2930
	21st to end	Night	6% 13% 5% 12% 8% 6% 5% 5% 6% 7% 28%	3000
December	1st to 10th	Night	10% 16% 6% 13% 7% 5% 4 4 5% 6% 25%	4890
	11th to 20th	Night	6% 16% 6% 13% 7% 6% 6% 4 7% 8% 22%	5550
	21st to end	Night	3 7% 3 9% 6% 5% 5% 5% 7% 8% 42%	7458

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	52% 8% 13% 18% 10% 1	3179
	11th to 20th	Day	47% 6% 11% 13% 20% 3	3180
	21st to end	Day	45% 8% 19% 23% 6%	3800
February	1st to 10th	Day	54% 6% 15% 15% 10% 1	1600
	11th to 20th	Day	52% 9% 13% 16% 9%	1725
	21st to end	Day	51% 9% 14% 18% 8% 1	1544
March	1st to 10th	Day	44% 8% 19% 19% 10%	4518
	11th to 20th	Day	45% 8% 14% 22% 11%	4972
	21st to end	Day	56% 8% 11% 19% 7%	5544
April	1st to 10th	Day	49% 8% 16% 18% 8% 1	2498
	11th to 20th	Day	49% 8% 14% 19% 9%	2570
	21st to end	Day	45% 10% 16% 21% 6% 2	2537
May	1st to 10th	Day	50% 9% 12% 22% 6%	4580
	11th to 20th	Day	46% 12% 14% 21% 8%	4698
	21st to end	Day	46% 13% 16% 17% 8%	5162
June	1st to 10th	Day	47% 9% 15% 21% 7% 1	2850
	11th to 20th	Day	54% 10% 15% 15% 5%	2850
	21st to end	Day	36% 13% 22% 22% 6% 1	2850
July	1st to 10th	Day	30% 8% 17% 29% 15% 2	4666
	11th to 20th	Day	31% 10% 17% 29% 13%	4659
	21st to end	Day	33% 8% 20% 25% 13% 1	4976
August	1st to 10th	Day	37% 10% 17% 33% 3	4462
	11th to 20th	Day	32% 9% 24% 28% 6%	4161
	21st to end	Day	34% 8% 28% 24% 5%	4520
September	1st to 10th	Day	36% 9% 21% 24% 8% 2	2405
	11th to 20th	Day	40% 6% 18% 29% 7%	2090
	21st to end	Day	36% 9% 19% 25% 9% 2	2090
October	1st to 10th	Day	40% 7% 20% 26% 6%	3298
	11th to 20th	Day	41% 7% 17% 25% 10%	2909
	21st to end	Day	43% 7% 15% 29% 5%	3075
November	1st to 10th	Day	54% 9% 14% 15% 6% 1	1568
	11th to 20th	Day	51% 8% 16% 19% 6%	1466
	21st to end	Day	50% 10% 14% 19% 6% 1	1400
December	1st to 10th	Day	59% 6% 18% 12% 4 1	2290
	11th to 20th	Day	56% 9% 17% 14% 4 1	2644
	21st to end	Day	37% 5% 12% 26% 16% 2	3498
January	1st to 10th	Night	55% 7% 14% 15% 8% 1	6766
	11th to 20th	Night	47% 6% 13% 16% 16% 2	6780
	21st to end	Night	47% 7% 17% 22% 7%	7200
February	1st to 10th	Night	54% 7% 12% 18% 9% 1	2800
	11th to 20th	Night	49% 9% 14% 16% 11% 1	2571
	21st to end	Night	46% 9% 13% 20% 11% 1	2085
March	1st to 10th	Night	44% 8% 18% 22% 7%	5376
	11th to 20th	Night	47% 8% 17% 18% 9% 1	5027
	21st to end	Night	57% 10% 10% 15% 7%	5429
April	1st to 10th	Night	45% 11% 13% 19% 11% 1	1901
	11th to 20th	Night	52% 8% 12% 18% 8% 2	1781
	21st to end	Night	44% 10% 15% 19% 10% 1	1759
May	1st to 10th	Night	56% 7% 9% 20% 8% 1	2376
	11th to 20th	Night	44% 14% 15% 19% 8% 1	2199
	21st to end	Night	49% 14% 16% 12% 8% 1	2414
June	1st to 10th	Night	49% 11% 14% 18% 8% 1	1330
	11th to 20th	Night	56% 11% 15% 13% 5%	1330
	21st to end	Night	39% 12% 22% 21% 5% 1	1330
July	1st to 10th	Night	36% 9% 17% 22% 15% 2	2185
	11th to 20th	Night	34% 10% 16% 27% 11% 1	2178
	21st to end	Night	34% 9% 21% 26% 10%	2337
August	1st to 10th	Night	37% 11% 18% 31% 2	2440
	11th to 20th	Night	38% 9% 23% 22% 8% 1	2740
	21st to end	Night	36% 9% 21% 29% 5%	3146
September	1st to 10th	Night	37% 9% 16% 24% 12% 2	1772
	11th to 20th	Night	39% 6% 16% 27% 9% 3	2090
	21st to end	Night	36% 10% 14% 24% 13% 3	2090
October	1st to 10th	Night	38% 6% 20% 26% 8%	3676
	11th to 20th	Night	39% 7% 15% 31% 8% 1	4017
	21st to end	Night	42% 9% 19% 24% 6%	4457
November	1st to 10th	Night	53% 7% 13% 19% 7% 1	2725
	11th to 20th	Night	52% 9% 14% 17% 7% 1	2930
	21st to end	Night	52% 8% 16% 17% 6% 1	3000
December	1st to 10th	Night	61% 6% 14% 13% 5% 1	4890
	11th to 20th	Night	58% 8% 17% 12% 5%	5547
	21st to end	Night	37% 7% 15% 23% 16% 3	7458

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	4 9% 30% 35% 19% 5%	200
	11th to 20th	Day	7% 7% 35% 35% 13% 4	200
	21st to end	Day	11% 10% 30% 28% 15% 6%	220
February	1st to 10th	Day	15% 9% 28% 32% 14% 3	200
	11th to 20th	Day	10% 5% 30% 36% 15% 4	281
	21st to end	Day	5% 6% 33% 34% 17% 6%	308
March	1st to 10th	Day	10% 8% 30% 31% 19% 2	500
	11th to 20th	Day	7% 6% 32% 34% 15% 6%	500
	21st to end	Day	15% 7% 26% 33% 15% 3	550
April	1st to 10th	Day	10% 13% 32% 30% 12% 3	500
	11th to 20th	Day	15% 12% 23% 30% 15% 5%	492
	21st to end	Day	14% 10% 27% 30% 14% 4	481
May	1st to 10th	Day	15% 10% 22% 33% 15% 6%	599
	11th to 20th	Day	10% 6% 26% 32% 20% 5%	675
	21st to end	Day	16% 4 23% 30% 20% 7%	734
June	1st to 10th	Day	18% 8% 25% 31% 16% 3	680
	11th to 20th	Day	19% 8% 22% 25% 20% 6%	680
	21st to end	Day	12% 5% 20% 30% 23% 10%	680
July	1st to 10th	Day	11% 3 18% 34% 23% 11%	671
	11th to 20th	Day	11% 4 21% 29% 26% 9%	668
	21st to end	Day	9% 6% 17% 31% 27% 11%	739
August	1st to 10th	Day	12% 2 20% 31% 22% 12%	540
	11th to 20th	Day	9% 5% 19% 33% 26% 8%	477
	21st to end	Day	10% 7% 20% 29% 25% 9%	539
September	1st to 10th	Day	14% 9% 24% 27% 20% 6%	490
	11th to 20th	Day	20% 6% 24% 29% 18% 4	490
	21st to end	Day	13% 14% 26% 27% 17% 3	490
October	1st to 10th	Day	15% 7% 28% 28% 16% 5%	376
	11th to 20th	Day	11% 8% 32% 28% 18% 3	300
	21st to end	Day	14% 11% 31% 31% 10% 3	330
November	1st to 10th	Day	15% 8% 29% 31% 15% 3	300
	11th to 20th	Day	11% 6% 35% 33% 13% 2	233
	21st to end	Day	4 6% 38% 35% 12% 6%	200
December	1st to 10th	Day	9% 8% 28% 34% 17% 5%	200
	11th to 20th	Day	9% 10% 30% 33% 15% 3	200
	21st to end	Day	7% 6% 21% 40% 20% 5%	220
January	1st to 10th	Night	9% 9% 32% 35% 14% 1	1000
	11th to 20th	Night	11% 9% 35% 33% 12% 2	1000
	21st to end	Night	13% 11% 34% 30% 10% 2	985
February	1st to 10th	Night	7% 10% 26% 38% 18% 2	800
	11th to 20th	Night	10% 6% 34% 35% 15%	784
	21st to end	Night	8% 5% 30% 36% 19% 4	660
March	1st to 10th	Night	9% 5% 28% 40% 17% 2	800
	11th to 20th	Night	10% 5% 31% 37% 15% 3	800
	21st to end	Night	14% 4 28% 36% 14% 3	880
April	1st to 10th	Night	11% 7% 30% 36% 14% 2	701
	11th to 20th	Night	14% 8% 28% 37% 12% 1	593
	21st to end	Night	15% 7% 27% 36% 15% 1	587
May	1st to 10th	Night	15% 9% 25% 36% 12% 2	432
	11th to 20th	Night	11% 6% 25% 40% 17% 1	374
	21st to end	Night	19% 4 26% 32% 17% 2	411
June	1st to 10th	Night	17% 8% 26% 33% 13% 2	380
	11th to 20th	Night	21% 5% 24% 32% 17% 2	380
	21st to end	Night	12% 4 21% 37% 25% 2	380
July	1st to 10th	Night	14% 1 16% 44% 24% 1	370
	11th to 20th	Night	11% 4 21% 41% 22% 1	368
	21st to end	Night	11% 4 18% 37% 27% 2	416
August	1st to 10th	Night	11% 4 20% 32% 27% 6%	378
	11th to 20th	Night	12% 4 18% 36% 29% 2	504
	21st to end	Night	11% 3 23% 38% 25% 1	627
September	1st to 10th	Night	14% 2 19% 42% 19% 2	613
	11th to 20th	Night	16% 4 21% 40% 17% 1	760
	21st to end	Night	11% 4 31% 41% 11% 2	760
October	1st to 10th	Night	14% 5% 28% 38% 14% 1	760
	11th to 20th	Night	12% 6% 35% 34% 12% 1	760
	21st to end	Night	9% 8% 35% 35% 12% 1	836
November	1st to 10th	Night	17% 6% 33% 33% 10% 1	970
	11th to 20th	Night	12% 8% 36% 30% 10% 2	1000
	21st to end	Night	10% 6% 38% 34% 11% 1	1000
December	1st to 10th	Night	13% 9% 31% 31% 13% 3	1000
	11th to 20th	Night	11% 6% 36% 33% 14% 2	1000
	21st to end	Night	9% 4 34% 35% 16% 3	1100

Page generated at 2025-04-23 07:25:05. Version ac07

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