Red Deer
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Red Deer clear sky chart from 2005-11-06 to 2025-07-06.

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% 5% 5% 5% 4 6% 8% 36%	123911
	Night	7% 10% 4 10% 6% 5% 5% 4 6% 8% 33%	123597
Transparency	Day	44% 7% 15% 23% 9% 1	123655
	Night	47% 7% 14% 22% 9% 1	123497
Seeing	Day	12% 7% 25% 32% 19% 6%	16253
	Night	12% 6% 29% 37% 15% 2	25295

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	3 11% 5% 14% 8% 6% 6% 4 6% 7% 29%	3179
	11th to 20th	Day	4 10% 5% 11% 7% 6% 7% 6% 7% 9% 29%	3159
	21st to end	Day	4 10% 5% 9% 5% 5% 4 4 6% 8% 38%	3930
February	1st to 10th	Day	7% 13% 5% 11% 6% 7% 5% 4 6% 8% 27%	1600
	11th to 20th	Day	6% 13% 6% 13% 7% 6% 6% 5% 6% 7% 25%	1719
	21st to end	Day	4 12% 5% 12% 9% 7% 7% 6% 6% 8% 26%	1575
March	1st to 10th	Day	3 9% 5% 12% 7% 5% 5% 4 6% 10% 35%	4518
	11th to 20th	Day	5% 11% 5% 10% 6% 4 4 3 6% 10% 36%	4948
	21st to end	Day	9% 19% 6% 12% 5% 5% 5% 4 6% 7% 22%	5568
April	1st to 10th	Day	8% 12% 4 8% 7% 6% 6% 5% 7% 8% 29%	2475
	11th to 20th	Day	11% 13% 3 10% 6% 5% 5% 4 7% 8% 28%	2570
	21st to end	Day	11% 11% 4 8% 6% 4 5% 4 6% 9% 31%	2600
May	1st to 10th	Day	13% 9% 3 7% 4 5% 5% 4 6% 7% 36%	6412
	11th to 20th	Day	13% 11% 4 10% 6% 5% 6% 5% 7% 8% 25%	6734
	21st to end	Day	12% 7% 3 7% 5% 5% 5% 4 6% 7% 38%	7405
June	1st to 10th	Day	15% 6% 2 7% 5% 5% 6% 5% 7% 9% 31%	3000
	11th to 20th	Day	19% 9% 3 8% 6% 5% 6% 6% 6% 8% 25%	3000
	21st to end	Day	10% 5% 2 6% 5% 6% 6% 6% 8% 10% 37%	3000
July	1st to 10th	Day	9% 5% 2 5% 3 4 4 4 6% 9% 50%	4816
	11th to 20th	Day	9% 4 2 4 4 4 4 4 6% 10% 49%	4740
	21st to end	Day	8% 5% 2 5% 4 4 4 4 7% 9% 50%	5138
August	1st to 10th	Day	10% 5% 3 7% 5% 5% 5% 5% 6% 8% 42%	4401
	11th to 20th	Day	8% 5% 2 5% 4 5% 6% 5% 8% 11% 41%	4115
	21st to end	Day	11% 5% 2 5% 4 4 5% 4 7% 9% 45%	4521
September	1st to 10th	Day	12% 6% 2 6% 4 4 5% 4 6% 8% 43%	2386
	11th to 20th	Day	16% 8% 2 6% 3 3 3 2 7% 8% 41%	2090
	21st to end	Day	9% 8% 2 7% 5% 4 5% 4 6% 8% 44%	2090
October	1st to 10th	Day	8% 8% 3 8% 5% 4 5% 5% 7% 8% 40%	3330
	11th to 20th	Day	8% 7% 3 7% 4 5% 6% 5% 7% 10% 37%	2889
	21st to end	Day	8% 9% 3 9% 7% 5% 5% 4 5% 6% 40%	3101
November	1st to 10th	Day	7% 16% 6% 10% 6% 5% 5% 5% 6% 7% 27%	1592
	11th to 20th	Day	5% 15% 5% 11% 7% 4 5% 3 6% 7% 33%	1480
	21st to end	Day	4 13% 3 11% 7% 7% 6% 4 7% 9% 30%	1400
December	1st to 10th	Day	8% 13% 4 11% 7% 7% 5% 4 5% 9% 26%	2290
	11th to 20th	Day	7% 12% 5% 13% 7% 8% 6% 5% 6% 6% 25%	2642
	21st to end	Day	3 7% 4 10% 6% 4 5% 4 7% 10% 40%	3498
January	1st to 10th	Night	2 12% 6% 14% 9% 7% 6% 5% 6% 7% 26%	6766
	11th to 20th	Night	3 11% 4 12% 7% 6% 6% 5% 6% 6% 33%	6739
	21st to end	Night	4 11% 5% 10% 6% 5% 5% 5% 7% 8% 35%	7072
February	1st to 10th	Night	5% 13% 5% 13% 7% 7% 5% 4 6% 8% 28%	2800
	11th to 20th	Night	6% 12% 6% 11% 8% 6% 6% 5% 6% 7% 26%	2567
	21st to end	Night	5% 11% 4 10% 8% 6% 6% 4 6% 8% 32%	2054
March	1st to 10th	Night	3 10% 4 12% 7% 6% 6% 5% 7% 9% 31%	5376
	11th to 20th	Night	4 9% 4 10% 7% 6% 7% 6% 9% 10% 28%	5050
	21st to end	Night	9% 17% 8% 16% 6% 5% 5% 3 6% 6% 20%	5403
April	1st to 10th	Night	7% 12% 4 9% 7% 6% 6% 5% 7% 7% 31%	1925
	11th to 20th	Night	9% 13% 4 10% 7% 6% 5% 4 6% 7% 28%	1781
	21st to end	Night	9% 11% 4 8% 5% 5% 6% 5% 7% 9% 30%	1800
May	1st to 10th	Night	17% 11% 3 7% 5% 4 4 4 5% 6% 35%	3553
	11th to 20th	Night	13% 10% 4 10% 7% 6% 6% 5% 7% 7% 25%	3159
	21st to end	Night	12% 8% 3 9% 6% 6% 7% 5% 6% 7% 31%	3470
June	1st to 10th	Night	17% 9% 3 9% 5% 5% 5% 4 7% 8% 28%	1400
	11th to 20th	Night	15% 10% 3 9% 7% 7% 5% 6% 7% 7% 25%	1400
	21st to end	Night	8% 5% 3 8% 6% 6% 6% 6% 7% 10% 36%	1400
July	1st to 10th	Night	10% 6% 2 7% 6% 4 5% 4 6% 8% 41%	2255
	11th to 20th	Night	6% 4 2 5% 4 4 5% 5% 9% 10% 46%	2220
	21st to end	Night	8% 5% 2 5% 4 4 5% 4 7% 10% 45%	2414
August	1st to 10th	Night	13% 6% 2 6% 4 5% 5% 3 5% 9% 42%	2526
	11th to 20th	Night	8% 6% 2 6% 4 5% 5% 5% 8% 11% 40%	2719
	21st to end	Night	13% 6% 2 6% 4 4 4 4 6% 8% 43%	3146
September	1st to 10th	Night	9% 6% 3 6% 5% 4 6% 4 7% 7% 44%	1791
	11th to 20th	Night	15% 8% 2 6% 4 4 5% 4 5% 8% 40%	2090
	21st to end	Night	8% 7% 3 8% 4 4 5% 4 6% 8% 44%	2090
October	1st to 10th	Night	6% 7% 3 7% 4 6% 5% 4 6% 8% 44%	3645
	11th to 20th	Night	7% 9% 3 7% 5% 5% 5% 4 6% 8% 40%	4024
	21st to end	Night	8% 10% 4 8% 5% 5% 6% 3 7% 7% 36%	4457
November	1st to 10th	Night	9% 15% 4 10% 6% 4 5% 5% 6% 7% 29%	2687
	11th to 20th	Night	6% 12% 5% 12% 7% 6% 6% 4 6% 8% 28%	2920
	21st to end	Night	5% 12% 4 11% 7% 5% 5% 5% 7% 8% 30%	3000
December	1st to 10th	Night	9% 13% 5% 11% 7% 6% 5% 4 6% 7% 27%	4890
	11th to 20th	Night	5% 14% 5% 14% 8% 6% 6% 4 6% 8% 23%	5550
	21st to end	Night	3 9% 3 9% 7% 5% 5% 4 7% 8% 40%	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	53% 6% 11% 18% 11% 1	3179
	11th to 20th	Day	49% 6% 10% 13% 18% 4	3180
	21st to end	Day	43% 6% 15% 28% 8%	3930
February	1st to 10th	Day	53% 5% 13% 16% 11% 1	1600
	11th to 20th	Day	56% 6% 12% 17% 8% 1	1728
	21st to end	Day	54% 6% 11% 20% 9%	1575
March	1st to 10th	Day	44% 6% 16% 22% 12%	4518
	11th to 20th	Day	43% 7% 13% 22% 15% 1	4949
	21st to end	Day	60% 5% 10% 17% 8%	5568
April	1st to 10th	Day	50% 8% 15% 18% 8% 1	2475
	11th to 20th	Day	51% 7% 12% 20% 9% 1	2570
	21st to end	Day	49% 7% 14% 23% 6% 2	2600
May	1st to 10th	Day	45% 6% 9% 24% 15% 2	6412
	11th to 20th	Day	51% 8% 15% 20% 6%	6738
	21st to end	Day	42% 8% 18% 23% 9% 1	7406
June	1st to 10th	Day	46% 7% 16% 22% 8% 1	3000
	11th to 20th	Day	54% 9% 14% 18% 4 1	3000
	21st to end	Day	39% 10% 21% 24% 5% 1	3000
July	1st to 10th	Day	30% 6% 19% 30% 13% 2	4742
	11th to 20th	Day	30% 7% 18% 36% 9%	4659
	21st to end	Day	29% 7% 18% 29% 14% 2	4976
August	1st to 10th	Day	38% 8% 17% 28% 8%	4384
	11th to 20th	Day	33% 9% 25% 26% 8%	4156
	21st to end	Day	34% 7% 25% 28% 6% 1	4520
September	1st to 10th	Day	37% 7% 20% 24% 10% 3	2386
	11th to 20th	Day	40% 7% 15% 29% 9% 1	2090
	21st to end	Day	38% 8% 16% 25% 11% 3	2090
October	1st to 10th	Day	41% 5% 19% 28% 6% 1	3330
	11th to 20th	Day	41% 6% 17% 24% 11% 1	2889
	21st to end	Day	43% 5% 10% 34% 7%	3101
November	1st to 10th	Day	53% 8% 13% 17% 7% 1	1592
	11th to 20th	Day	50% 6% 14% 20% 9% 1	1480
	21st to end	Day	49% 8% 17% 18% 7% 2	1400
December	1st to 10th	Day	57% 5% 17% 15% 5% 1	2290
	11th to 20th	Day	56% 7% 16% 16% 4 1	2644
	21st to end	Day	38% 5% 12% 26% 17% 3	3498
January	1st to 10th	Night	55% 6% 11% 19% 7% 2	6766
	11th to 20th	Night	49% 5% 12% 16% 15% 3	6780
	21st to end	Night	44% 7% 16% 25% 8% 1	7072
February	1st to 10th	Night	54% 6% 10% 19% 11% 1	2800
	11th to 20th	Night	54% 6% 12% 15% 12% 1	2568
	21st to end	Night	48% 6% 12% 21% 11% 2	2054
March	1st to 10th	Night	46% 7% 15% 21% 11%	5376
	11th to 20th	Night	45% 8% 16% 22% 9% 1	5050
	21st to end	Night	63% 6% 8% 16% 7%	5403
April	1st to 10th	Night	48% 8% 14% 19% 10% 1	1925
	11th to 20th	Night	51% 6% 12% 22% 8% 1	1781
	21st to end	Night	45% 9% 15% 21% 8% 1	1800
May	1st to 10th	Night	49% 6% 9% 21% 14% 2	3550
	11th to 20th	Night	53% 9% 13% 18% 6%	3159
	21st to end	Night	47% 9% 15% 19% 8% 1	3470
June	1st to 10th	Night	52% 9% 13% 17% 8% 1	1400
	11th to 20th	Night	54% 10% 14% 16% 5% 1	1400
	21st to end	Night	40% 8% 20% 23% 7% 1	1400
July	1st to 10th	Night	38% 7% 18% 22% 13% 1	2220
	11th to 20th	Night	29% 10% 18% 33% 7% 4	2178
	21st to end	Night	32% 9% 16% 30% 13% 1	2337
August	1st to 10th	Night	39% 8% 17% 30% 7%	2519
	11th to 20th	Night	35% 9% 23% 26% 6% 1	2744
	21st to end	Night	37% 6% 20% 29% 7% 1	3146
September	1st to 10th	Night	35% 8% 15% 26% 12% 3	1791
	11th to 20th	Night	41% 7% 14% 26% 9% 3	2090
	21st to end	Night	36% 6% 17% 25% 14% 3	2090
October	1st to 10th	Night	38% 5% 19% 26% 12% 1	3645
	11th to 20th	Night	40% 6% 16% 29% 8% 1	4024
	21st to end	Night	44% 6% 15% 27% 7% 1	4457
November	1st to 10th	Night	52% 6% 12% 21% 8% 2	2687
	11th to 20th	Night	51% 6% 14% 19% 9% 1	2920
	21st to end	Night	49% 7% 17% 18% 7% 2	3000
December	1st to 10th	Night	56% 5% 16% 15% 6% 1	4890
	11th to 20th	Night	57% 7% 16% 15% 5%	5547
	21st to end	Night	40% 5% 11% 26% 16% 4	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	6% 7% 26% 35% 18% 10%	200
	11th to 20th	Day	6% 6% 36% 34% 15% 4	200
	21st to end	Day	7% 7% 34% 27% 18% 7%	220
February	1st to 10th	Day	10% 10% 23% 37% 16% 6%	200
	11th to 20th	Day	9% 5% 29% 40% 12% 5%	283
	21st to end	Day	5% 4 32% 34% 19% 5%	339
March	1st to 10th	Day	8% 7% 30% 34% 17% 4	500
	11th to 20th	Day	7% 5% 30% 35% 18% 5%	500
	21st to end	Day	15% 7% 28% 28% 17% 5%	550
April	1st to 10th	Day	10% 10% 31% 32% 12% 5%	500
	11th to 20th	Day	15% 10% 25% 28% 17% 4	492
	21st to end	Day	15% 9% 24% 33% 15% 4	500
May	1st to 10th	Day	16% 10% 23% 30% 16% 5%	603
	11th to 20th	Day	11% 8% 23% 34% 19% 5%	725
	21st to end	Day	16% 4 20% 32% 22% 7%	789
June	1st to 10th	Day	18% 7% 22% 35% 15% 4	730
	11th to 20th	Day	20% 8% 21% 31% 16% 4	730
	21st to end	Day	12% 4 21% 33% 21% 9%	730
July	1st to 10th	Day	12% 4 17% 34% 24% 9%	697
	11th to 20th	Day	14% 4 17% 32% 26% 7%	668
	21st to end	Day	8% 4 19% 32% 28% 9%	739
August	1st to 10th	Day	11% 5% 18% 33% 23% 9%	487
	11th to 20th	Day	9% 5% 18% 34% 28% 7%	477
	21st to end	Day	10% 8% 19% 30% 24% 8%	539
September	1st to 10th	Day	13% 6% 29% 25% 22% 4	490
	11th to 20th	Day	20% 6% 22% 29% 18% 5%	490
	21st to end	Day	11% 12% 30% 27% 15% 5%	490
October	1st to 10th	Day	18% 6% 25% 29% 14% 8%	395
	11th to 20th	Day	11% 9% 34% 28% 14% 4	300
	21st to end	Day	12% 9% 34% 29% 13% 2	330
November	1st to 10th	Day	14% 8% 28% 34% 13% 3	300
	11th to 20th	Day	12% 6% 32% 37% 13% 1	240
	21st to end	Day	7% 5% 35% 32% 13% 9%	200
December	1st to 10th	Day	11% 6% 32% 32% 17% 5%	200
	11th to 20th	Day	8% 6% 39% 31% 15% 2	200
	21st to end	Day	9% 6% 22% 32% 24% 7%	220
January	1st to 10th	Night	9% 5% 36% 33% 15% 1	1000
	11th to 20th	Night	12% 7% 34% 34% 12% 1	1000
	21st to end	Night	11% 9% 31% 36% 11% 2	935
February	1st to 10th	Night	10% 8% 27% 37% 18% 2	800
	11th to 20th	Night	9% 6% 34% 36% 14%	784
	21st to end	Night	9% 4 25% 38% 19% 4	660
March	1st to 10th	Night	10% 3 30% 39% 15% 2	800
	11th to 20th	Night	9% 4 31% 40% 14% 3	800
	21st to end	Night	14% 6% 25% 39% 13% 2	880
April	1st to 10th	Night	12% 6% 32% 33% 16% 1	725
	11th to 20th	Night	14% 9% 28% 39% 9%	593
	21st to end	Night	15% 7% 30% 35% 13% 1	600
May	1st to 10th	Night	20% 7% 24% 35% 12% 1	465
	11th to 20th	Night	12% 7% 26% 38% 17% 1	394
	21st to end	Night	21% 4 24% 33% 16% 2	433
June	1st to 10th	Night	19% 8% 27% 34% 10% 3	400
	11th to 20th	Night	18% 5% 27% 34% 17%	400
	21st to end	Night	11% 3 23% 40% 22% 2	400
July	1st to 10th	Night	13% 2 14% 48% 22% 1	380
	11th to 20th	Night	13% 4 19% 42% 22% 1	368
	21st to end	Night	8% 5% 15% 40% 29% 2	416
August	1st to 10th	Night	13% 2 17% 34% 30% 3	378
	11th to 20th	Night	11% 5% 17% 42% 24% 2	508
	21st to end	Night	12% 4 21% 40% 23%	627
September	1st to 10th	Night	12% 3 24% 42% 17% 1	641
	11th to 20th	Night	19% 3 19% 38% 19% 1	760
	21st to end	Night	11% 5% 29% 39% 15% 2	760
October	1st to 10th	Night	14% 4 27% 38% 15% 1	760
	11th to 20th	Night	12% 6% 31% 37% 13% 1	760
	21st to end	Night	13% 8% 33% 35% 11% 1	836
November	1st to 10th	Night	16% 7% 32% 33% 11% 1	932
	11th to 20th	Night	11% 9% 37% 31% 11% 2	1000
	21st to end	Night	10% 4 38% 35% 12% 2	1000
December	1st to 10th	Night	13% 7% 29% 34% 15% 3	1000
	11th to 20th	Night	10% 6% 34% 36% 12% 2	1000
	21st to end	Night	11% 4 32% 35% 15% 2	1100

Page generated at 2025-07-02 23:30:14. Version ac07

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