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 2026-10-29.

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% 8% 3 8% 5% 5% 5% 4 6% 9% 37%	154790
	Night	7% 10% 4 10% 6% 5% 5% 4 6% 8% 34%	146035
Transparency	Day	43% 6% 16% 25% 9% 1	154490
	Night	46% 6% 15% 22% 9% 1	145919
Seeing	Day	13% 6% 25% 32% 19% 6%	18030
	Night	12% 6% 29% 37% 15% 2	26940

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 12% 6% 14% 8% 6% 6% 5% 6% 7% 28%	4125
	11th to 20th	Day	3 8% 4 10% 6% 6% 7% 5% 7% 8% 36%	4119
	21st to end	Day	4 10% 5% 10% 5% 5% 5% 4 6% 8% 38%	5084
February	1st to 10th	Day	7% 13% 5% 11% 6% 7% 5% 4 6% 9% 27%	1680
	11th to 20th	Day	5% 13% 5% 12% 7% 6% 6% 5% 6% 8% 27%	1807
	21st to end	Day	4 12% 5% 12% 9% 7% 7% 6% 6% 8% 25%	1651
March	1st to 10th	Day	3 9% 5% 13% 7% 5% 5% 4 6% 10% 35%	4618
	11th to 20th	Day	5% 11% 5% 10% 6% 4 4 3 6% 10% 36%	5057
	21st to end	Day	9% 19% 6% 12% 5% 5% 5% 4 6% 7% 22%	5691
April	1st to 10th	Day	9% 12% 4 8% 7% 6% 6% 5% 7% 8% 29%	2599
	11th to 20th	Day	11% 13% 4 10% 6% 5% 5% 4 7% 8% 27%	2700
	21st to end	Day	11% 12% 4 9% 5% 4 5% 4 6% 8% 32%	2730
May	1st to 10th	Day	11% 8% 2 6% 4 5% 5% 4 7% 8% 40%	8316
	11th to 20th	Day	12% 11% 4 10% 6% 5% 6% 5% 7% 9% 27%	8755
	21st to end	Day	12% 7% 3 7% 5% 6% 6% 4 6% 8% 36%	9649
June	1st to 10th	Day	16% 7% 2 8% 5% 5% 6% 5% 7% 8% 30%	3150
	11th to 20th	Day	18% 8% 3 9% 6% 5% 6% 6% 6% 8% 24%	3150
	21st to end	Day	11% 5% 2 6% 5% 6% 5% 6% 8% 10% 36%	3150
July	1st to 10th	Day	8% 5% 2 5% 4 4 4 4 6% 10% 49%	8820
	11th to 20th	Day	10% 5% 2 6% 4 4 5% 5% 7% 10% 43%	8820
	21st to end	Day	9% 5% 2 5% 4 4 4 4 7% 8% 49%	9569
August	1st to 10th	Day	9% 5% 2 6% 4 4 5% 4 7% 10% 43%	6441
	11th to 20th	Day	9% 6% 3 6% 4 4 6% 5% 7% 10% 40%	6054
	21st to end	Day	9% 4 2 4 4 4 5% 4 7% 9% 50%	6570
September	1st to 10th	Day	12% 6% 2 6% 4 4 5% 4 6% 8% 43%	2636
	11th to 20th	Day	14% 7% 2 5% 3 4 3 2 6% 8% 44%	2310
	21st to end	Day	8% 8% 2 7% 4 4 5% 4 6% 8% 44%	2310
October	1st to 10th	Day	8% 8% 3 8% 4 4 5% 5% 7% 7% 41%	3540
	11th to 20th	Day	8% 8% 3 7% 4 5% 6% 5% 7% 9% 38%	3073
	21st to end	Day	8% 9% 3 8% 7% 5% 5% 4 5% 6% 40%	3272
November	1st to 10th	Day	7% 16% 5% 10% 6% 5% 5% 5% 6% 7% 27%	1673
	11th to 20th	Day	5% 14% 5% 10% 6% 5% 5% 3 6% 7% 33%	1554
	21st to end	Day	4 13% 3 11% 7% 6% 6% 4 7% 9% 29%	1470
December	1st to 10th	Day	8% 14% 4 10% 8% 7% 5% 4 5% 9% 25%	2360
	11th to 20th	Day	7% 12% 5% 13% 8% 7% 6% 5% 6% 6% 25%	2712
	21st to end	Day	3 7% 4 10% 6% 4 5% 4 7% 10% 39%	3575
January	1st to 10th	Night	5% 13% 6% 14% 8% 7% 6% 4 6% 7% 24%	8768
	11th to 20th	Night	3 10% 4 10% 6% 5% 6% 5% 6% 7% 38%	8779
	21st to end	Night	3 10% 4 11% 6% 5% 6% 5% 7% 9% 34%	9156
February	1st to 10th	Night	5% 13% 5% 13% 7% 6% 5% 5% 6% 8% 28%	2940
	11th to 20th	Night	6% 12% 6% 11% 8% 6% 6% 5% 6% 7% 26%	2699
	21st to end	Night	5% 12% 4 10% 8% 6% 6% 4 6% 8% 32%	2153
March	1st to 10th	Night	3 10% 4 12% 7% 6% 6% 5% 7% 9% 30%	5496
	11th to 20th	Night	4 9% 4 10% 7% 6% 7% 6% 9% 10% 28%	5161
	21st to end	Night	8% 17% 8% 16% 6% 5% 5% 3 6% 6% 20%	5522
April	1st to 10th	Night	8% 12% 4 9% 7% 6% 6% 5% 7% 7% 30%	2021
	11th to 20th	Night	9% 13% 4 10% 7% 6% 5% 4 6% 7% 28%	1871
	21st to end	Night	9% 12% 4 8% 5% 5% 6% 5% 7% 9% 31%	1890
May	1st to 10th	Night	14% 10% 3 7% 5% 4 4 4 5% 7% 36%	4611
	11th to 20th	Night	12% 9% 4 10% 7% 6% 6% 5% 8% 8% 26%	4105
	21st to end	Night	12% 7% 3 8% 6% 6% 6% 4 6% 9% 32%	4522
June	1st to 10th	Night	17% 9% 3 9% 5% 5% 5% 4 7% 8% 27%	1470
	11th to 20th	Night	15% 9% 3 9% 7% 7% 6% 6% 7% 7% 24%	1470
	21st to end	Night	9% 5% 3 8% 6% 6% 6% 6% 7% 10% 35%	1470
July	1st to 10th	Night	8% 5% 2 6% 5% 5% 5% 4 6% 9% 45%	4140
	11th to 20th	Night	8% 5% 2 6% 4 4 4 4 7% 9% 46%	4140
	21st to end	Night	9% 5% 2 6% 5% 5% 5% 4 7% 10% 43%	4499
August	1st to 10th	Night	14% 8% 2 6% 4 5% 4 3 5% 8% 41%	3706
	11th to 20th	Night	11% 7% 2 6% 4 5% 6% 5% 7% 10% 36%	4004
	21st to end	Night	10% 5% 2 6% 4 5% 5% 4 6% 9% 44%	4578
September	1st to 10th	Night	9% 6% 3 6% 4 4 6% 4 7% 8% 43%	1981
	11th to 20th	Night	14% 7% 2 6% 3 4 5% 4 5% 8% 43%	2310
	21st to end	Night	8% 6% 3 7% 4 4 5% 4 6% 9% 44%	2310
October	1st to 10th	Night	6% 6% 3 7% 5% 6% 5% 4 6% 8% 44%	3875
	11th to 20th	Night	7% 9% 3 7% 5% 5% 5% 4 6% 8% 41%	4280
	21st to end	Night	7% 10% 4 8% 5% 5% 6% 3 7% 7% 37%	4704
November	1st to 10th	Night	9% 15% 4 10% 6% 4 5% 5% 6% 7% 29%	2825
	11th to 20th	Night	6% 12% 5% 12% 8% 6% 6% 4 6% 8% 28%	3066
	21st to end	Night	5% 12% 4 11% 7% 5% 5% 5% 7% 8% 30%	3150
December	1st to 10th	Night	9% 13% 5% 11% 7% 6% 5% 4 5% 7% 27%	5040
	11th to 20th	Night	5% 14% 5% 14% 8% 6% 6% 4 6% 8% 23%	5700
	21st to end	Night	3 9% 3 9% 7% 5% 5% 4 7% 8% 40%	7623

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	54% 5% 10% 16% 13% 1	4125
	11th to 20th	Day	44% 5% 13% 16% 18% 4	4140
	21st to end	Day	44% 5% 16% 29% 7%	5085
February	1st to 10th	Day	52% 5% 13% 17% 12% 1	1680
	11th to 20th	Day	54% 6% 12% 18% 10% 1	1816
	21st to end	Day	54% 6% 11% 20% 9%	1651
March	1st to 10th	Day	44% 6% 16% 22% 12%	4618
	11th to 20th	Day	43% 7% 13% 22% 14% 1	5058
	21st to end	Day	60% 5% 10% 17% 8%	5691
April	1st to 10th	Day	50% 8% 15% 18% 8% 1	2599
	11th to 20th	Day	51% 7% 12% 20% 9% 1	2700
	21st to end	Day	49% 7% 13% 23% 6% 2	2730
May	1st to 10th	Day	41% 5% 10% 30% 13% 1	8316
	11th to 20th	Day	51% 7% 12% 22% 8%	8759
	21st to end	Day	44% 7% 18% 22% 8% 1	9650
June	1st to 10th	Day	48% 7% 15% 21% 8% 1	3150
	11th to 20th	Day	55% 9% 13% 18% 4 1	3150
	21st to end	Day	39% 10% 21% 24% 5% 1	3150
July	1st to 10th	Day	30% 6% 21% 32% 9% 1	8746
	11th to 20th	Day	36% 7% 19% 27% 9% 1	8739
	21st to end	Day	31% 6% 21% 29% 12% 2	9362
August	1st to 10th	Day	35% 8% 20% 28% 10%	6424
	11th to 20th	Day	37% 8% 24% 25% 6%	6095
	21st to end	Day	30% 6% 21% 35% 8% 1	6569
September	1st to 10th	Day	37% 6% 19% 25% 9% 3	2636
	11th to 20th	Day	38% 7% 14% 30% 10% 1	2310
	21st to end	Day	37% 8% 16% 26% 11% 3	2310
October	1st to 10th	Day	40% 5% 19% 29% 6% 1	3540
	11th to 20th	Day	40% 6% 16% 24% 13% 2	3073
	21st to end	Day	43% 5% 10% 33% 8% 1	3272
November	1st to 10th	Day	53% 8% 13% 17% 7% 1	1673
	11th to 20th	Day	50% 6% 14% 21% 9% 1	1554
	21st to end	Day	49% 8% 17% 18% 7% 2	1470
December	1st to 10th	Day	57% 5% 17% 15% 5% 1	2360
	11th to 20th	Day	56% 7% 16% 16% 4 1	2714
	21st to end	Day	39% 5% 12% 25% 17% 3	3575
January	1st to 10th	Night	58% 6% 10% 16% 9% 1	8769
	11th to 20th	Night	44% 4 16% 19% 14% 3	8820
	21st to end	Night	45% 6% 18% 23% 7%	9156
February	1st to 10th	Night	53% 6% 10% 18% 11% 1	2940
	11th to 20th	Night	54% 6% 12% 16% 12% 1	2700
	21st to end	Night	49% 5% 12% 21% 11% 1	2153
March	1st to 10th	Night	46% 6% 15% 21% 11%	5496
	11th to 20th	Night	45% 8% 15% 22% 9% 1	5161
	21st to end	Night	63% 6% 8% 16% 7%	5522
April	1st to 10th	Night	48% 8% 15% 18% 10% 1	2021
	11th to 20th	Night	52% 6% 12% 22% 8% 1	1871
	21st to end	Night	46% 9% 14% 22% 8% 1	1890
May	1st to 10th	Night	46% 6% 10% 23% 14% 2	4608
	11th to 20th	Night	52% 8% 12% 20% 8%	4105
	21st to end	Night	46% 8% 18% 20% 7% 1	4526
June	1st to 10th	Night	53% 9% 13% 17% 8% 1	1470
	11th to 20th	Night	55% 9% 14% 16% 5% 1	1470
	21st to end	Night	41% 8% 20% 23% 7% 1	1470
July	1st to 10th	Night	34% 7% 22% 27% 9% 1	4105
	11th to 20th	Night	33% 8% 18% 30% 8% 3	4098
	21st to end	Night	34% 9% 20% 27% 10% 1	4401
August	1st to 10th	Night	41% 6% 17% 28% 7%	3699
	11th to 20th	Night	40% 9% 22% 24% 4	4029
	21st to end	Night	35% 6% 20% 31% 7% 1	4578
September	1st to 10th	Night	35% 8% 15% 27% 12% 3	1981
	11th to 20th	Night	38% 7% 13% 28% 10% 3	2310
	21st to end	Night	35% 6% 17% 26% 14% 3	2310
October	1st to 10th	Night	38% 5% 19% 26% 12% 1	3875
	11th to 20th	Night	40% 6% 15% 29% 9% 1	4280
	21st to end	Night	44% 6% 15% 27% 7% 1	4704
November	1st to 10th	Night	52% 6% 12% 21% 8% 2	2825
	11th to 20th	Night	50% 6% 14% 19% 9% 1	3066
	21st to end	Night	48% 7% 17% 18% 7% 2	3150
December	1st to 10th	Night	57% 5% 16% 15% 6% 1	5040
	11th to 20th	Night	57% 7% 16% 15% 5%	5697
	21st to end	Night	40% 5% 11% 26% 15% 4	7623

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% 6% 28% 33% 17% 9%	220
	11th to 20th	Day	7% 7% 37% 33% 14% 3	220
	21st to end	Day	8% 7% 35% 27% 17% 7%	242
February	1st to 10th	Day	10% 9% 24% 37% 15% 5%	220
	11th to 20th	Day	9% 5% 28% 39% 14% 5%	311
	21st to end	Day	6% 4 33% 33% 18% 6%	367
March	1st to 10th	Day	9% 7% 32% 32% 16% 4	540
	11th to 20th	Day	6% 4 34% 34% 16% 5%	540
	21st to end	Day	14% 8% 29% 27% 17% 4	594
April	1st to 10th	Day	11% 9% 30% 31% 12% 5%	540
	11th to 20th	Day	15% 10% 26% 27% 17% 4	532
	21st to end	Day	15% 9% 24% 33% 15% 5%	540
May	1st to 10th	Day	15% 10% 23% 31% 16% 5%	648
	11th to 20th	Day	11% 8% 24% 33% 19% 5%	775
	21st to end	Day	15% 4 20% 33% 22% 7%	844
June	1st to 10th	Day	19% 6% 22% 33% 15% 4	780
	11th to 20th	Day	20% 8% 21% 30% 16% 4	780
	21st to end	Day	14% 3 20% 32% 21% 9%	780
July	1st to 10th	Day	13% 3 17% 34% 23% 9%	771
	11th to 20th	Day	14% 4 19% 32% 24% 7%	768
	21st to end	Day	9% 4 19% 34% 27% 8%	849
August	1st to 10th	Day	12% 5% 19% 32% 24% 9%	567
	11th to 20th	Day	9% 4 20% 33% 27% 6%	557
	21st to end	Day	9% 7% 19% 31% 25% 9%	627
September	1st to 10th	Day	15% 5% 27% 27% 22% 4	570
	11th to 20th	Day	18% 5% 20% 31% 20% 6%	570
	21st to end	Day	11% 11% 32% 27% 15% 4	570
October	1st to 10th	Day	17% 6% 25% 32% 14% 7%	465
	11th to 20th	Day	11% 9% 34% 29% 14% 4	360
	21st to end	Day	12% 10% 36% 28% 12% 2	387
November	1st to 10th	Day	14% 8% 31% 32% 12% 3	330
	11th to 20th	Day	11% 5% 33% 37% 13% 1	264
	21st to end	Day	7% 5% 35% 32% 13% 9%	220
December	1st to 10th	Day	11% 5% 33% 31% 15% 4	220
	11th to 20th	Day	8% 6% 41% 29% 14% 2	220
	21st to end	Day	10% 7% 22% 34% 22% 6%	242
January	1st to 10th	Night	10% 5% 36% 33% 14% 1	1050
	11th to 20th	Night	12% 7% 35% 33% 11% 1	1050
	21st to end	Night	11% 9% 31% 36% 12% 2	982
February	1st to 10th	Night	10% 8% 27% 37% 17% 1	840
	11th to 20th	Night	9% 6% 33% 37% 14%	824
	21st to end	Night	10% 4 26% 38% 19% 4	692
March	1st to 10th	Night	10% 3 32% 39% 14% 2	840
	11th to 20th	Night	9% 4 33% 39% 13% 3	840
	21st to end	Night	15% 6% 26% 38% 13% 2	924
April	1st to 10th	Night	13% 6% 32% 32% 15% 1	761
	11th to 20th	Night	14% 9% 28% 39% 10%	623
	21st to end	Night	16% 7% 29% 35% 13%	630
May	1st to 10th	Night	19% 7% 25% 36% 12% 1	488
	11th to 20th	Night	12% 6% 27% 37% 17% 1	414
	21st to end	Night	21% 4 23% 34% 16% 2	455
June	1st to 10th	Night	20% 8% 26% 34% 10% 3	420
	11th to 20th	Night	17% 5% 27% 35% 16%	420
	21st to end	Night	12% 2 23% 40% 21% 2	420
July	1st to 10th	Night	13% 1 15% 48% 21% 1	410
	11th to 20th	Night	13% 3 20% 42% 21% 1	408
	21st to end	Night	8% 5% 15% 41% 29% 2	460
August	1st to 10th	Night	14% 2 18% 33% 29% 3	418
	11th to 20th	Night	11% 4 17% 41% 24% 2	562
	21st to end	Night	11% 4 21% 41% 22% 1	693
September	1st to 10th	Night	12% 3 23% 44% 17% 1	709
	11th to 20th	Night	17% 3 19% 40% 20% 1	840
	21st to end	Night	11% 4 31% 38% 14% 1	840
October	1st to 10th	Night	14% 4 27% 40% 15% 1	840
	11th to 20th	Night	12% 7% 32% 36% 13% 1	840
	21st to end	Night	13% 8% 33% 35% 11% 1	912
November	1st to 10th	Night	16% 7% 33% 32% 10% 1	980
	11th to 20th	Night	11% 8% 36% 31% 11% 2	1050
	21st to end	Night	10% 4 37% 36% 12% 2	1050
December	1st to 10th	Night	14% 7% 30% 33% 14% 2	1050
	11th to 20th	Night	10% 7% 34% 35% 12% 1	1050
	21st to end	Night	11% 4 33% 35% 15% 2	1155

Page generated at 2026-10-26 01:37:45. Version ac07

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