Fort McMurray
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fort McMurray clear sky chart from 2005-11-06 to 2024-11-05.

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	11% 9% 3 8% 6% 5% 5% 4 6% 7% 34%	105884
	Night	9% 10% 4 10% 6% 6% 5% 4 6% 7% 33%	101676
Transparency	Day	46% 9% 16% 22% 7%	105609
	Night	48% 9% 16% 21% 6%	101597
Seeing	Day	15% 11% 28% 29% 15% 3	16429
	Night	14% 8% 30% 32% 14% 2	24756

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	7% 11% 5% 16% 12% 8% 8% 5% 5% 6% 16%	1679
	11th to 20th	Day	4 11% 4 10% 8% 8% 10% 8% 8% 6% 23%	2146
	21st to end	Day	8% 15% 6% 16% 7% 6% 5% 4 5% 5% 23%	2442
February	1st to 10th	Day	6% 12% 5% 11% 7% 8% 6% 5% 7% 8% 24%	1430
	11th to 20th	Day	5% 10% 4 10% 7% 7% 8% 5% 5% 7% 31%	1602
	21st to end	Day	3 9% 5% 11% 9% 8% 6% 5% 8% 8% 29%	1413
March	1st to 10th	Day	3 12% 4 8% 6% 7% 7% 5% 6% 9% 34%	3064
	11th to 20th	Day	6% 8% 4 9% 6% 6% 7% 5% 8% 9% 33%	3489
	21st to end	Day	4 13% 5% 11% 5% 4 4 3 6% 6% 37%	3825
April	1st to 10th	Day	9% 13% 4 10% 7% 5% 5% 4 6% 7% 30%	2446
	11th to 20th	Day	10% 12% 4 11% 7% 6% 5% 4 5% 6% 31%	2440
	21st to end	Day	11% 12% 4 10% 6% 6% 6% 4 6% 8% 29%	2601
May	1st to 10th	Day	12% 10% 4 9% 6% 5% 5% 4 6% 6% 33%	4740
	11th to 20th	Day	20% 9% 3 7% 6% 5% 5% 4 5% 6% 30%	4694
	21st to end	Day	13% 8% 3 8% 6% 6% 6% 5% 7% 7% 33%	5438
June	1st to 10th	Day	17% 8% 3 8% 6% 5% 5% 5% 7% 7% 30%	3194
	11th to 20th	Day	19% 9% 3 8% 6% 5% 5% 4 6% 7% 28%	3230
	21st to end	Day	14% 8% 2 7% 5% 5% 5% 4 7% 8% 34%	3230
July	1st to 10th	Day	8% 4 2 6% 5% 5% 6% 6% 8% 10% 38%	5380
	11th to 20th	Day	6% 4 2 5% 3 4 5% 4 7% 8% 51%	5018
	21st to end	Day	16% 5% 2 5% 4 4 5% 4 7% 8% 39%	5138
August	1st to 10th	Day	8% 4 2 6% 4 4 5% 4 6% 8% 49%	4720
	11th to 20th	Day	14% 7% 2 6% 5% 5% 5% 5% 6% 8% 37%	4336
	21st to end	Day	14% 6% 2 6% 5% 5% 5% 4 6% 7% 39%	4521
September	1st to 10th	Day	17% 8% 2 7% 4 4 5% 4 5% 8% 36%	2426
	11th to 20th	Day	14% 9% 2 6% 5% 5% 5% 4 7% 6% 37%	2164
	21st to end	Day	12% 8% 3 8% 5% 5% 5% 4 5% 7% 39%	2085
October	1st to 10th	Day	10% 10% 3 9% 5% 5% 5% 5% 8% 8% 33%	3170
	11th to 20th	Day	11% 12% 4 9% 6% 5% 5% 4 6% 7% 32%	2936
	21st to end	Day	10% 15% 5% 12% 5% 4 4 3 5% 6% 32%	2799
November	1st to 10th	Day	11% 14% 6% 13% 7% 4 4 4 4 6% 27%	1506
	11th to 20th	Day	12% 13% 6% 14% 8% 7% 5% 4 5% 4 23%	1320
	21st to end	Day	8% 14% 6% 12% 9% 5% 5% 3 4 5% 29%	1140
December	1st to 10th	Day	5% 12% 7% 14% 9% 9% 6% 4 4 7% 24%	1140
	11th to 20th	Day	9% 16% 5% 11% 7% 5% 5% 2 5% 6% 29%	1244
	21st to end	Day	5% 8% 4 7% 5% 6% 5% 4 7% 8% 41%	1738
January	1st to 10th	Night	7% 14% 6% 16% 9% 7% 7% 5% 6% 5% 20%	5266
	11th to 20th	Night	4 10% 4 12% 8% 8% 10% 8% 8% 6% 21%	4750
	21st to end	Night	5% 14% 6% 14% 6% 6% 6% 4 5% 6% 27%	5214
February	1st to 10th	Night	5% 11% 5% 11% 9% 7% 7% 5% 6% 6% 28%	2765
	11th to 20th	Night	6% 12% 5% 13% 8% 6% 6% 5% 5% 6% 28%	2464
	21st to end	Night	3 8% 5% 13% 7% 7% 6% 5% 8% 8% 29%	2041
March	1st to 10th	Night	3 11% 5% 10% 6% 6% 5% 4 7% 9% 33%	3791
	11th to 20th	Night	6% 8% 3 8% 6% 6% 6% 5% 8% 8% 35%	3490
	21st to end	Night	7% 10% 6% 12% 5% 5% 4 4 4 5% 37%	3828
April	1st to 10th	Night	10% 14% 3 11% 6% 5% 5% 4 5% 6% 32%	1730
	11th to 20th	Night	8% 9% 4 8% 5% 6% 7% 6% 7% 7% 33%	1691
	21st to end	Night	10% 12% 5% 10% 7% 6% 5% 4 4 6% 31%	1577
May	1st to 10th	Night	15% 10% 2 7% 5% 4 5% 4 5% 7% 35%	2220
	11th to 20th	Night	19% 9% 3 7% 4 5% 5% 4 7% 8% 29%	2199
	21st to end	Night	11% 7% 3 8% 6% 6% 5% 5% 8% 8% 34%	2135
June	1st to 10th	Night	17% 7% 2 8% 4 5% 4 3 7% 9% 33%	983
	11th to 20th	Night	15% 9% 3 7% 6% 7% 5% 4 7% 8% 28%	950
	21st to end	Night	12% 5% 2 7% 7% 3 4 5% 6% 8% 40%	950
July	1st to 10th	Night	6% 4 2 6% 5% 5% 6% 6% 7% 12% 39%	1580
	11th to 20th	Night	5% 3 1 4 3 3 4 5% 7% 10% 55%	1939
	21st to end	Night	15% 5% 2 4 3 4 4 3 7% 10% 45%	2414
August	1st to 10th	Night	7% 5% 2 6% 4 5% 6% 4 7% 9% 46%	2210
	11th to 20th	Night	12% 6% 2 6% 4 4 5% 4 7% 8% 41%	2493
	21st to end	Night	12% 6% 2 6% 4 5% 4 3 6% 8% 44%	3146
September	1st to 10th	Night	14% 6% 3 8% 4 4 4 4 7% 7% 38%	1754
	11th to 20th	Night	12% 7% 3 7% 6% 4 4 4 6% 8% 38%	2014
	21st to end	Night	11% 8% 2 6% 5% 4 5% 4 7% 7% 41%	2095
October	1st to 10th	Night	13% 10% 3 7% 4 4 4 3 4 6% 42%	3800
	11th to 20th	Night	11% 10% 4 8% 4 5% 5% 4 6% 7% 36%	3988
	21st to end	Night	12% 15% 4 11% 6% 6% 5% 4 5% 5% 25%	4728
November	1st to 10th	Night	13% 15% 5% 10% 7% 4 4 3 5% 5% 28%	2669
	11th to 20th	Night	11% 13% 5% 13% 8% 6% 4 4 5% 5% 25%	2859
	21st to end	Night	8% 15% 6% 13% 7% 5% 4 4 6% 6% 26%	3040
December	1st to 10th	Night	7% 12% 4 13% 8% 8% 6% 4 5% 6% 26%	3040
	11th to 20th	Night	9% 15% 5% 13% 7% 7% 6% 5% 5% 7% 22%	3945
	21st to end	Night	4 8% 3 9% 6% 6% 6% 5% 5% 7% 40%	5918

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	63% 11% 13% 9% 4	1679
	11th to 20th	Day	53% 10% 14% 17% 5% 1	2167
	21st to end	Day	61% 10% 12% 13% 4	2442
February	1st to 10th	Day	55% 9% 12% 15% 8%	1430
	11th to 20th	Day	50% 10% 15% 19% 6%	1610
	21st to end	Day	51% 7% 16% 20% 7%	1413
March	1st to 10th	Day	44% 8% 17% 25% 5%	3064
	11th to 20th	Day	42% 11% 18% 21% 9%	3490
	21st to end	Day	45% 7% 10% 27% 11%	3825
April	1st to 10th	Day	52% 8% 12% 18% 10% 1	2446
	11th to 20th	Day	52% 7% 10% 19% 11% 1	2440
	21st to end	Day	51% 7% 12% 22% 7%	2601
May	1st to 10th	Day	48% 8% 11% 20% 12% 1	4740
	11th to 20th	Day	51% 8% 12% 17% 11%	4698
	21st to end	Day	44% 13% 12% 21% 10%	5439
June	1st to 10th	Day	50% 9% 12% 21% 8%	3194
	11th to 20th	Day	53% 9% 12% 19% 6%	3230
	21st to end	Day	46% 9% 17% 20% 7% 1	3230
July	1st to 10th	Day	35% 10% 23% 25% 6%	5296
	11th to 20th	Day	27% 8% 18% 35% 12%	4927
	21st to end	Day	40% 9% 22% 26% 3	4976
August	1st to 10th	Day	32% 8% 21% 36% 3	4702
	11th to 20th	Day	43% 9% 21% 20% 6% 1	4381
	21st to end	Day	43% 8% 24% 23% 2	4520
September	1st to 10th	Day	45% 10% 19% 21% 5%	2426
	11th to 20th	Day	46% 8% 22% 21% 4	2164
	21st to end	Day	43% 9% 17% 23% 7%	2085
October	1st to 10th	Day	46% 7% 17% 26% 3	3170
	11th to 20th	Day	50% 6% 16% 24% 3	2936
	21st to end	Day	53% 7% 19% 19% 2	2799
November	1st to 10th	Day	59% 8% 14% 16% 3	1506
	11th to 20th	Day	63% 10% 12% 12% 2	1320
	21st to end	Day	57% 8% 16% 16% 3 1	1140
December	1st to 10th	Day	59% 9% 12% 15% 4	1140
	11th to 20th	Day	57% 6% 11% 23% 3	1245
	21st to end	Day	39% 7% 18% 28% 7% 1	1738
January	1st to 10th	Night	61% 9% 13% 14% 4	5266
	11th to 20th	Night	54% 11% 15% 15% 4 1	4791
	21st to end	Night	55% 10% 17% 14% 5%	5214
February	1st to 10th	Night	53% 8% 15% 16% 8%	2765
	11th to 20th	Night	55% 8% 14% 18% 6%	2466
	21st to end	Night	48% 8% 18% 18% 8%	2041
March	1st to 10th	Night	44% 9% 17% 26% 4	3791
	11th to 20th	Night	43% 10% 15% 27% 5%	3490
	21st to end	Night	46% 7% 10% 21% 15% 1	3828
April	1st to 10th	Night	51% 8% 11% 18% 11% 1	1730
	11th to 20th	Night	44% 8% 13% 18% 15% 2	1691
	21st to end	Night	52% 8% 9% 21% 9% 1	1577
May	1st to 10th	Night	45% 9% 10% 24% 12% 1	2220
	11th to 20th	Night	48% 9% 13% 19% 10% 1	2199
	21st to end	Night	41% 12% 12% 22% 12% 1	2135
June	1st to 10th	Night	46% 8% 14% 21% 11%	983
	11th to 20th	Night	52% 9% 12% 21% 7% 1	950
	21st to end	Night	40% 9% 17% 21% 11% 1	950
July	1st to 10th	Night	33% 9% 25% 28% 4 1	1555
	11th to 20th	Night	23% 9% 16% 37% 15% 1	1907
	21st to end	Night	34% 7% 24% 29% 6%	2337
August	1st to 10th	Night	32% 7% 18% 40% 3	2203
	11th to 20th	Night	38% 9% 22% 23% 7%	2514
	21st to end	Night	38% 7% 29% 23% 3	3146
September	1st to 10th	Night	42% 9% 22% 21% 6%	1754
	11th to 20th	Night	42% 10% 17% 25% 7%	2014
	21st to end	Night	39% 9% 19% 23% 9% 1	2095
October	1st to 10th	Night	44% 5% 14% 28% 9%	3800
	11th to 20th	Night	47% 6% 17% 26% 4	3988
	21st to end	Night	60% 7% 15% 14% 3	4728
November	1st to 10th	Night	58% 7% 14% 17% 4	2669
	11th to 20th	Night	59% 11% 15% 13% 2	2859
	21st to end	Night	58% 9% 15% 15% 3	3040
December	1st to 10th	Night	58% 8% 14% 14% 5%	3040
	11th to 20th	Night	59% 9% 15% 13% 3	3943
	21st to end	Night	40% 9% 17% 23% 10% 1	5918

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	9% 6% 28% 40% 14% 2	180
	11th to 20th	Day	10% 12% 28% 36% 12% 2	180
	21st to end	Day	11% 12% 32% 32% 11% 3	198
February	1st to 10th	Day	12% 7% 37% 27% 13% 4	180
	11th to 20th	Day	8% 11% 32% 30% 14% 5%	240
	21st to end	Day	8% 12% 39% 27% 11% 3	225
March	1st to 10th	Day	8% 12% 36% 28% 14% 2	384
	11th to 20th	Day	9% 17% 33% 27% 13% 1	460
	21st to end	Day	11% 13% 32% 31% 11% 2	506
April	1st to 10th	Day	18% 14% 34% 23% 7% 3	460
	11th to 20th	Day	16% 15% 25% 30% 12% 2	452
	21st to end	Day	18% 13% 31% 24% 12% 2	588
May	1st to 10th	Day	13% 13% 27% 29% 14% 4	653
	11th to 20th	Day	13% 12% 26% 29% 18% 2	675
	21st to end	Day	14% 11% 23% 33% 14% 4	734
June	1st to 10th	Day	20% 14% 26% 26% 12% 2	834
	11th to 20th	Day	20% 10% 25% 29% 13% 3	870
	21st to end	Day	14% 6% 24% 30% 20% 5%	870
July	1st to 10th	Day	12% 8% 23% 34% 20% 4	856
	11th to 20th	Day	12% 7% 21% 30% 22% 7%	771
	21st to end	Day	15% 7% 23% 26% 21% 8%	739
August	1st to 10th	Day	14% 8% 18% 30% 22% 8%	676
	11th to 20th	Day	13% 10% 30% 29% 16% 3	570
	21st to end	Day	17% 6% 27% 29% 18% 3	539
September	1st to 10th	Day	20% 11% 29% 25% 13% 3	490
	11th to 20th	Day	18% 10% 26% 31% 13% 1	490
	21st to end	Day	16% 14% 30% 25% 13% 2	485
October	1st to 10th	Day	16% 18% 27% 27% 9% 3	300
	11th to 20th	Day	16% 16% 39% 23% 6% 1	300
	21st to end	Day	22% 12% 33% 22% 8% 2	330
November	1st to 10th	Day	17% 12% 32% 25% 13% 2	276
	11th to 20th	Day	18% 9% 38% 25% 8% 2	180
	21st to end	Day	16% 12% 36% 23% 11% 3	180
December	1st to 10th	Day	8% 14% 27% 36% 13% 2	180
	11th to 20th	Day	14% 10% 36% 27% 11% 2	180
	21st to end	Day	7% 3 30% 34% 21% 5%	198
January	1st to 10th	Night	12% 8% 33% 32% 14% 1	1040
	11th to 20th	Night	12% 8% 33% 35% 10% 2	962
	21st to end	Night	13% 10% 33% 32% 10% 1	1045
February	1st to 10th	Night	10% 8% 31% 32% 16% 3	865
	11th to 20th	Night	13% 7% 34% 33% 11% 2	744
	21st to end	Night	6% 6% 33% 38% 16% 1	628
March	1st to 10th	Night	8% 9% 34% 34% 13% 2	760
	11th to 20th	Night	15% 9% 33% 31% 12%	760
	21st to end	Night	13% 8% 30% 34% 13% 2	836
April	1st to 10th	Night	13% 10% 33% 32% 11% 2	571
	11th to 20th	Night	12% 9% 31% 33% 14% 2	563
	21st to end	Night	14% 9% 31% 32% 12% 2	565
May	1st to 10th	Night	16% 10% 24% 32% 16% 2	380
	11th to 20th	Night	13% 10% 29% 34% 13% 2	374
	21st to end	Night	13% 7% 25% 39% 13% 3	411
June	1st to 10th	Night	21% 5% 24% 36% 13% 1	380
	11th to 20th	Night	18% 7% 23% 31% 19% 2	380
	21st to end	Night	13% 4 18% 36% 24% 4	380
July	1st to 10th	Night	10% 5% 21% 38% 24% 1	370
	11th to 20th	Night	11% 4 22% 35% 23% 5%	368
	21st to end	Night	14% 3 14% 38% 24% 7%	416
August	1st to 10th	Night	12% 4 16% 33% 30% 5%	378
	11th to 20th	Night	9% 4 28% 35% 22% 2	465
	21st to end	Night	18% 4 24% 35% 19% 1	627
September	1st to 10th	Night	18% 6% 25% 30% 18% 3	570
	11th to 20th	Night	15% 6% 22% 39% 16% 1	684
	21st to end	Night	14% 9% 30% 34% 12% 1	760
October	1st to 10th	Night	21% 9% 33% 25% 9% 2	760
	11th to 20th	Night	17% 9% 33% 29% 10% 2	760
	21st to end	Night	22% 11% 30% 27% 9% 1	993
November	1st to 10th	Night	18% 8% 31% 30% 11% 1	950
	11th to 20th	Night	18% 8% 36% 28% 9% 2	950
	21st to end	Night	13% 13% 37% 27% 8% 1	950
December	1st to 10th	Night	13% 9% 32% 31% 14% 1	950
	11th to 20th	Night	14% 8% 32% 35% 9% 2	1017
	21st to end	Night	10% 7% 28% 33% 19% 2	1144

Page generated at 2024-11-03 00:11:18. Version ac07

Copyright © 2024 Attilla Danko.