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 2024-11-03.

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% 35%	101977
	Night	8% 10% 4 10% 6% 5% 5% 5% 6% 8% 33%	97099
Transparency	Day	44% 7% 16% 23% 9% 1	101721
	Night	46% 7% 14% 21% 9% 2	97002
Seeing	Day	12% 7% 25% 32% 19% 6%	15413
	Night	12% 6% 29% 37% 15% 2	24388

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% 5% 12% 7% 6% 6% 4 7% 7% 30%	2219
	11th to 20th	Day	5% 9% 4 11% 7% 5% 8% 6% 8% 9% 29%	2199
	21st to end	Day	5% 10% 4 9% 6% 6% 4 4 5% 9% 37%	2734
February	1st to 10th	Day	8% 14% 5% 10% 5% 7% 5% 4 6% 9% 27%	1520
	11th to 20th	Day	6% 14% 6% 13% 7% 6% 6% 5% 5% 7% 26%	1630
	21st to end	Day	4 12% 6% 12% 9% 6% 7% 5% 6% 7% 25%	1498
March	1st to 10th	Day	3 11% 6% 16% 9% 6% 5% 4 5% 8% 25%	3138
	11th to 20th	Day	5% 11% 3 7% 4 3 5% 4 7% 12% 40%	3451
	21st to end	Day	7% 20% 7% 13% 6% 6% 5% 3 6% 6% 23%	3881
April	1st to 10th	Day	9% 12% 4 9% 7% 6% 6% 5% 7% 8% 29%	2351
	11th to 20th	Day	11% 14% 3 10% 6% 5% 5% 4 7% 7% 27%	2440
	21st to end	Day	12% 11% 4 9% 6% 4 5% 4 6% 9% 31%	2470
May	1st to 10th	Day	18% 12% 3 8% 5% 5% 5% 4 6% 7% 28%	4481
	11th to 20th	Day	10% 11% 4 9% 6% 5% 6% 5% 7% 8% 29%	4694
	21st to end	Day	15% 9% 3 9% 6% 6% 6% 5% 7% 7% 27%	5161
June	1st to 10th	Day	16% 7% 2 8% 5% 5% 6% 5% 7% 8% 30%	2850
	11th to 20th	Day	19% 9% 3 8% 6% 5% 6% 5% 6% 8% 25%	2850
	21st to end	Day	10% 5% 2 6% 5% 6% 5% 6% 8% 10% 37%	2850
July	1st to 10th	Day	9% 5% 2 5% 3 4 4 4 6% 9% 50%	4740
	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	12% 9% 3 8% 4 4 4 4 5% 7% 39%	1995
	11th to 20th	Day	10% 9% 4 8% 4 5% 6% 5% 6% 8% 36%	1745
	21st to end	Day	8% 12% 4 9% 7% 5% 5% 5% 6% 6% 33%	1881
November	1st to 10th	Day	7% 17% 6% 10% 6% 5% 6% 5% 6% 6% 27%	1528
	11th to 20th	Day	6% 15% 5% 11% 7% 4 5% 2 6% 7% 33%	1406
	21st to end	Day	4 12% 3 10% 8% 6% 6% 4 6% 9% 31%	1330
December	1st to 10th	Day	6% 14% 5% 11% 9% 7% 5% 3 4 8% 28%	1330
	11th to 20th	Day	4 12% 5% 13% 7% 7% 6% 6% 7% 7% 27%	1682
	21st to end	Day	4 9% 4 9% 5% 4 4 3 6% 11% 40%	2442
January	1st to 10th	Night	3 13% 6% 12% 8% 6% 6% 5% 7% 7% 27%	4726
	11th to 20th	Night	4 10% 4 13% 8% 6% 6% 6% 6% 6% 31%	4699
	21st to end	Night	4 13% 4 10% 6% 6% 6% 5% 7% 8% 30%	4954
February	1st to 10th	Night	6% 14% 5% 13% 7% 6% 5% 4 6% 8% 29%	2660
	11th to 20th	Night	6% 13% 6% 11% 8% 6% 6% 5% 6% 7% 26%	2436
	21st to end	Night	5% 12% 4 10% 8% 6% 6% 4 7% 8% 32%	1955
March	1st to 10th	Night	3 10% 5% 16% 9% 7% 7% 5% 7% 8% 24%	3736
	11th to 20th	Night	6% 8% 3 8% 6% 6% 6% 6% 8% 10% 34%	3527
	21st to end	Night	7% 17% 8% 18% 7% 5% 5% 4 6% 6% 18%	3768
April	1st to 10th	Night	8% 12% 4 9% 7% 7% 6% 5% 7% 7% 29%	1829
	11th to 20th	Night	9% 13% 4 10% 7% 6% 5% 4 6% 7% 28%	1691
	21st to end	Night	9% 11% 4 8% 5% 5% 6% 5% 7% 9% 30%	1710
May	1st to 10th	Night	22% 13% 4 8% 5% 4 4 4 5% 6% 26%	2481
	11th to 20th	Night	10% 9% 4 8% 6% 6% 6% 5% 7% 8% 30%	2199
	21st to end	Night	16% 9% 4 10% 7% 7% 8% 5% 6% 8% 20%	2414
June	1st to 10th	Night	17% 9% 3 8% 5% 5% 5% 4 7% 8% 27%	1330
	11th to 20th	Night	16% 9% 3 9% 7% 6% 6% 6% 7% 7% 24%	1330
	21st to end	Night	8% 5% 3 8% 6% 5% 6% 6% 7% 10% 36%	1330
July	1st to 10th	Night	10% 6% 2 7% 6% 5% 5% 4 6% 8% 41%	2220
	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	10% 8% 4 8% 4 6% 5% 4 5% 7% 40%	2185
	11th to 20th	Night	8% 9% 3 8% 6% 6% 5% 4 6% 8% 38%	2432
	21st to end	Night	7% 11% 4 10% 6% 5% 6% 4 7% 8% 32%	2717
November	1st to 10th	Night	9% 15% 4 10% 6% 5% 5% 5% 6% 7% 29%	2576
	11th to 20th	Night	6% 12% 5% 12% 7% 6% 6% 4 6% 8% 29%	2774
	21st to end	Night	5% 11% 4 10% 7% 5% 5% 5% 7% 8% 31%	2850
December	1st to 10th	Night	7% 12% 5% 11% 7% 6% 5% 4 5% 7% 31%	2850
	11th to 20th	Night	3 12% 5% 13% 8% 6% 6% 5% 6% 8% 28%	3510
	21st to end	Night	3 10% 3 8% 6% 4 4 4 6% 8% 43%	5214

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	50% 6% 13% 20% 10% 1	2219
	11th to 20th	Day	47% 7% 11% 14% 17% 4	2220
	21st to end	Day	42% 7% 15% 28% 7%	2734
February	1st to 10th	Day	52% 5% 14% 17% 11% 1	1520
	11th to 20th	Day	56% 7% 12% 16% 8% 1	1639
	21st to end	Day	55% 6% 11% 19% 9%	1498
March	1st to 10th	Day	55% 7% 13% 15% 10%	3138
	11th to 20th	Day	35% 8% 18% 23% 15% 1	3452
	21st to end	Day	60% 5% 12% 16% 6%	3881
April	1st to 10th	Day	51% 9% 15% 17% 8% 1	2351
	11th to 20th	Day	52% 7% 12% 20% 9%	2440
	21st to end	Day	49% 8% 14% 22% 5% 2	2470
May	1st to 10th	Day	54% 7% 10% 23% 6%	4481
	11th to 20th	Day	47% 9% 14% 21% 8%	4698
	21st to end	Day	51% 10% 16% 16% 7% 1	5162
June	1st to 10th	Day	48% 8% 16% 21% 7% 1	2850
	11th to 20th	Day	54% 9% 14% 18% 5% 1	2850
	21st to end	Day	38% 11% 21% 24% 6% 1	2850
July	1st to 10th	Day	30% 6% 19% 30% 13% 2	4666
	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	45% 5% 17% 24% 9% 1	1995
	11th to 20th	Day	43% 7% 17% 23% 10% 1	1745
	21st to end	Day	48% 7% 12% 23% 10% 1	1881
November	1st to 10th	Day	54% 8% 13% 17% 7% 1	1528
	11th to 20th	Day	50% 6% 14% 20% 9% 1	1406
	21st to end	Day	47% 8% 18% 18% 7% 2	1330
December	1st to 10th	Day	56% 6% 11% 16% 8% 2	1330
	11th to 20th	Day	50% 9% 16% 19% 6% 1	1684
	21st to end	Day	38% 5% 12% 22% 18% 4	2442
January	1st to 10th	Night	53% 7% 11% 19% 8% 2	4726
	11th to 20th	Night	50% 6% 11% 15% 14% 4	4740
	21st to end	Night	47% 8% 13% 23% 8% 1	4954
February	1st to 10th	Night	53% 7% 10% 19% 10% 1	2660
	11th to 20th	Night	54% 6% 12% 15% 11% 1	2437
	21st to end	Night	49% 6% 12% 21% 11% 2	1955
March	1st to 10th	Night	53% 8% 10% 20% 8%	3736
	11th to 20th	Night	39% 9% 19% 20% 10% 1	3527
	21st to end	Night	63% 7% 10% 14% 6% 1	3768
April	1st to 10th	Night	49% 8% 15% 18% 9% 1	1829
	11th to 20th	Night	52% 6% 12% 22% 8% 1	1691
	21st to end	Night	45% 9% 15% 21% 8% 1	1710
May	1st to 10th	Night	56% 7% 9% 21% 6%	2481
	11th to 20th	Night	46% 11% 12% 22% 9%	2199
	21st to end	Night	56% 11% 14% 12% 6% 1	2414
June	1st to 10th	Night	52% 9% 13% 17% 7% 1	1330
	11th to 20th	Night	54% 10% 14% 16% 5% 1	1330
	21st to end	Night	40% 8% 20% 23% 8% 1	1330
July	1st to 10th	Night	39% 7% 18% 21% 14% 1	2185
	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	43% 6% 16% 22% 12% 1	2185
	11th to 20th	Night	43% 6% 16% 23% 9% 2	2432
	21st to end	Night	47% 7% 16% 21% 8% 1	2717
November	1st to 10th	Night	52% 6% 12% 20% 8% 2	2576
	11th to 20th	Night	50% 6% 14% 19% 10% 1	2774
	21st to end	Night	47% 7% 18% 19% 7% 2	2850
December	1st to 10th	Night	51% 6% 11% 20% 10% 2	2850
	11th to 20th	Night	50% 8% 15% 21% 6%	3507
	21st to end	Night	37% 5% 12% 25% 15% 6%	5214

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	5% 6% 26% 35% 19% 9%	180
	11th to 20th	Day	6% 6% 37% 32% 16% 4	180
	21st to end	Day	7% 6% 33% 28% 20% 8%	198
February	1st to 10th	Day	11% 10% 22% 36% 16% 6%	180
	11th to 20th	Day	10% 6% 28% 39% 12% 6%	254
	21st to end	Day	5% 4 30% 35% 20% 6%	310
March	1st to 10th	Day	9% 8% 31% 32% 16% 4	460
	11th to 20th	Day	6% 5% 31% 35% 18% 5%	460
	21st to end	Day	14% 7% 27% 29% 17% 5%	506
April	1st to 10th	Day	10% 10% 32% 32% 11% 5%	460
	11th to 20th	Day	15% 9% 25% 29% 17% 5%	452
	21st to end	Day	15% 9% 24% 33% 14% 4	460
May	1st to 10th	Day	17% 9% 22% 30% 17% 5%	558
	11th to 20th	Day	10% 8% 24% 34% 19% 5%	675
	21st to end	Day	16% 4 19% 31% 22% 7%	734
June	1st to 10th	Day	18% 6% 23% 34% 15% 4	680
	11th to 20th	Day	21% 8% 21% 30% 15% 4	680
	21st to end	Day	12% 4 22% 33% 21% 10%	680
July	1st to 10th	Day	13% 4 17% 34% 24% 10%	671
	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% 9% 28% 34% 12% 4	276
	11th to 20th	Day	12% 6% 32% 38% 12% 1	216
	21st to end	Day	4 6% 36% 32% 13% 9%	180
December	1st to 10th	Day	9% 6% 32% 32% 17% 5%	180
	11th to 20th	Day	7% 6% 39% 31% 16% 1	180
	21st to end	Day	9% 6% 23% 33% 23% 7%	198
January	1st to 10th	Night	10% 5% 36% 34% 14% 1	950
	11th to 20th	Night	12% 7% 33% 35% 12% 1	950
	21st to end	Night	11% 9% 30% 36% 12% 2	889
February	1st to 10th	Night	10% 9% 27% 36% 18% 1	760
	11th to 20th	Night	10% 6% 33% 35% 15%	744
	21st to end	Night	10% 4 24% 38% 20% 4	628
March	1st to 10th	Night	10% 4 31% 39% 15% 2	760
	11th to 20th	Night	9% 4 32% 39% 14% 3	760
	21st to end	Night	14% 6% 25% 39% 14% 2	836
April	1st to 10th	Night	12% 7% 33% 33% 15% 1	689
	11th to 20th	Night	14% 9% 27% 40% 10%	563
	21st to end	Night	14% 8% 29% 36% 13% 1	570
May	1st to 10th	Night	20% 7% 24% 35% 13% 1	442
	11th to 20th	Night	11% 7% 26% 39% 16% 1	374
	21st to end	Night	21% 4 23% 33% 16% 2	411
June	1st to 10th	Night	19% 8% 25% 35% 10% 3	380
	11th to 20th	Night	17% 5% 27% 34% 17%	380
	21st to end	Night	11% 3 23% 40% 21% 2	380
July	1st to 10th	Night	13% 1 15% 48% 22% 1	370
	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% 12% 1	836
November	1st to 10th	Night	15% 8% 32% 33% 11% 1	893
	11th to 20th	Night	12% 8% 37% 31% 10% 2	950
	21st to end	Night	9% 4 38% 34% 12% 2	950
December	1st to 10th	Night	13% 7% 29% 34% 15% 3	950
	11th to 20th	Night	9% 6% 34% 36% 12% 2	950
	21st to end	Night	11% 4 32% 35% 15% 2	1045

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