Fort MacKay/Firebag Aerodrome
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fort MacKay/Firebag Aerodrome clear sky chart from 2005-11-06 to 2024-11-12.

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	10% 10% 4 9% 6% 5% 6% 5% 6% 7% 32%	105979
	Night	8% 10% 4 10% 7% 6% 6% 5% 7% 7% 30%	101722
Transparency	Day	47% 9% 16% 21% 7%	105703
	Night	49% 9% 16% 20% 6%	101644
Seeing	Day	15% 12% 30% 27% 12% 3	16513
	Night	13% 10% 33% 30% 12% 2	24830

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	5% 10% 4 18% 11% 12% 11% 6% 7% 5% 12%	1579
	11th to 20th	Day	3 9% 4 15% 8% 5% 9% 9% 12% 7% 18%	2110
	21st to end	Day	4 14% 6% 18% 9% 7% 6% 5% 6% 5% 19%	2442
February	1st to 10th	Day	4 10% 5% 12% 8% 9% 10% 7% 7% 8% 21%	1398
	11th to 20th	Day	5% 11% 4 12% 7% 9% 7% 6% 5% 5% 28%	1604
	21st to end	Day	2 8% 5% 11% 9% 8% 8% 7% 9% 8% 25%	1413
March	1st to 10th	Day	2 12% 4 10% 6% 6% 10% 6% 7% 8% 30%	3038
	11th to 20th	Day	5% 10% 4 10% 6% 6% 7% 5% 7% 8% 31%	3489
	21st to end	Day	3 9% 6% 13% 6% 5% 4 3 6% 7% 38%	3851
April	1st to 10th	Day	7% 13% 5% 12% 7% 4 6% 5% 5% 6% 30%	2437
	11th to 20th	Day	8% 12% 4 10% 8% 7% 5% 4 6% 6% 30%	2440
	21st to end	Day	9% 13% 4 11% 7% 6% 5% 5% 6% 7% 28%	2629
May	1st to 10th	Day	11% 11% 4 10% 6% 5% 5% 4 5% 6% 32%	4740
	11th to 20th	Day	17% 12% 3 8% 5% 5% 5% 3 5% 7% 28%	4720
	21st to end	Day	11% 8% 4 9% 5% 6% 7% 6% 7% 8% 30%	5509
June	1st to 10th	Day	16% 9% 3 9% 5% 5% 5% 5% 6% 7% 29%	3216
	11th to 20th	Day	18% 11% 3 8% 6% 4 5% 4 6% 7% 27%	3230
	21st to end	Day	14% 8% 3 7% 6% 5% 6% 5% 7% 8% 33%	3230
July	1st to 10th	Day	9% 5% 2 7% 6% 6% 6% 5% 9% 10% 36%	5380
	11th to 20th	Day	8% 5% 2 5% 4 4 5% 4 6% 9% 49%	5153
	21st to end	Day	16% 6% 2 6% 5% 4 5% 4 6% 9% 37%	5138
August	1st to 10th	Day	10% 5% 2 6% 4 4 5% 4 6% 9% 45%	4720
	11th to 20th	Day	17% 6% 2 6% 4 5% 5% 3 6% 9% 36%	4384
	21st to end	Day	17% 6% 2 7% 4 5% 5% 4 6% 8% 36%	4521
September	1st to 10th	Day	18% 9% 2 8% 4 4 5% 3 5% 7% 35%	2418
	11th to 20th	Day	14% 11% 3 7% 5% 5% 5% 5% 6% 7% 33%	2185
	21st to end	Day	12% 11% 4 8% 5% 5% 4 4 6% 7% 33%	2071
October	1st to 10th	Day	9% 14% 5% 11% 5% 4 5% 4 5% 7% 29%	3170
	11th to 20th	Day	11% 14% 4 11% 6% 4 3 3 5% 7% 32%	2945
	21st to end	Day	9% 14% 5% 14% 5% 4 3 3 5% 6% 31%	2764
November	1st to 10th	Day	9% 17% 5% 14% 8% 5% 4 4 4 6% 24%	1551
	11th to 20th	Day	10% 13% 5% 16% 12% 6% 6% 3 5% 6% 19%	1272
	21st to end	Day	9% 13% 6% 15% 8% 6% 6% 5% 5% 6% 22%	1140
December	1st to 10th	Day	5% 13% 6% 13% 11% 8% 9% 5% 6% 6% 19%	1140
	11th to 20th	Day	7% 14% 4 15% 8% 5% 6% 4 5% 6% 25%	1214
	21st to end	Day	4 7% 4 8% 7% 7% 6% 6% 6% 6% 40%	1738
January	1st to 10th	Night	4 12% 5% 15% 10% 8% 9% 6% 7% 6% 18%	5362
	11th to 20th	Night	3 8% 5% 11% 7% 8% 10% 10% 13% 8% 17%	4786
	21st to end	Night	4 14% 5% 17% 8% 6% 6% 4 6% 6% 23%	5214
February	1st to 10th	Night	3 10% 4 11% 8% 9% 10% 7% 7% 6% 25%	2798
	11th to 20th	Night	4 12% 6% 11% 8% 8% 8% 6% 7% 6% 26%	2463
	21st to end	Night	2 8% 5% 14% 10% 8% 6% 5% 9% 7% 27%	2041
March	1st to 10th	Night	2 11% 5% 11% 7% 7% 7% 5% 8% 8% 29%	3828
	11th to 20th	Night	6% 11% 4 9% 6% 5% 6% 5% 7% 8% 33%	3490
	21st to end	Night	4 10% 5% 13% 6% 5% 4 4 5% 6% 38%	3801
April	1st to 10th	Night	10% 11% 4 13% 6% 5% 5% 4 7% 8% 28%	1742
	11th to 20th	Night	7% 10% 5% 10% 6% 5% 6% 4 7% 7% 33%	1691
	21st to end	Night	8% 13% 5% 10% 6% 5% 5% 4 6% 6% 33%	1549
May	1st to 10th	Night	12% 10% 4 7% 5% 5% 5% 4 6% 7% 34%	2220
	11th to 20th	Night	16% 13% 4 7% 5% 5% 5% 4 7% 8% 28%	2172
	21st to end	Night	10% 8% 4 8% 5% 5% 6% 5% 8% 7% 34%	2066
June	1st to 10th	Night	17% 7% 2 7% 5% 5% 5% 4 7% 9% 32%	960
	11th to 20th	Night	18% 9% 4 7% 6% 5% 4 5% 7% 6% 30%	950
	21st to end	Night	14% 6% 1 6% 6% 5% 5% 5% 6% 9% 37%	950
July	1st to 10th	Night	6% 4 2 7% 4 5% 7% 6% 10% 11% 39%	1580
	11th to 20th	Night	6% 4 1 4 4 4 4 4 6% 7% 57%	1803
	21st to end	Night	15% 5% 1 5% 4 3 4 4 7% 10% 43%	2414
August	1st to 10th	Night	9% 4 1 4 4 5% 4 4 6% 8% 51%	2210
	11th to 20th	Night	12% 6% 2 6% 4 5% 5% 4 6% 9% 41%	2433
	21st to end	Night	14% 6% 2 6% 5% 4 5% 5% 5% 9% 40%	3146
September	1st to 10th	Night	15% 8% 4 6% 5% 4 4 4 6% 8% 36%	1762
	11th to 20th	Night	14% 7% 2 7% 4 5% 5% 4 7% 7% 37%	1991
	21st to end	Night	13% 9% 2 7% 4 5% 5% 4 7% 7% 37%	2109
October	1st to 10th	Night	12% 14% 4 7% 5% 4 4 3 5% 6% 37%	3800
	11th to 20th	Night	11% 13% 4 10% 5% 5% 5% 4 6% 7% 31%	3981
	21st to end	Night	10% 16% 6% 14% 7% 6% 5% 4 5% 5% 22%	4763
November	1st to 10th	Night	9% 14% 7% 14% 9% 5% 4 3 5% 5% 25%	2745
	11th to 20th	Night	10% 13% 5% 14% 10% 6% 5% 4 6% 6% 20%	2930
	21st to end	Night	8% 14% 6% 14% 9% 6% 6% 5% 6% 5% 22%	3040
December	1st to 10th	Night	5% 12% 5% 12% 11% 8% 8% 5% 7% 7% 21%	3040
	11th to 20th	Night	7% 14% 5% 13% 9% 9% 8% 6% 7% 7% 18%	3974
	21st to end	Night	3 8% 3 9% 7% 6% 6% 6% 7% 7% 39%	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	68% 10% 11% 8% 3	1579
	11th to 20th	Day	53% 10% 17% 15% 5% 1	2131
	21st to end	Day	63% 8% 12% 12% 4	2442
February	1st to 10th	Day	56% 9% 12% 14% 9%	1398
	11th to 20th	Day	53% 7% 15% 19% 5%	1613
	21st to end	Day	51% 9% 13% 19% 8%	1413
March	1st to 10th	Day	47% 9% 16% 24% 3	3038
	11th to 20th	Day	44% 11% 16% 21% 8%	3490
	21st to end	Day	42% 7% 11% 26% 14%	3851
April	1st to 10th	Day	51% 9% 12% 18% 10% 1	2437
	11th to 20th	Day	52% 6% 11% 20% 11% 1	2440
	21st to end	Day	52% 8% 11% 22% 7%	2629
May	1st to 10th	Day	47% 8% 14% 19% 12% 1	4740
	11th to 20th	Day	51% 9% 12% 17% 11%	4724
	21st to end	Day	43% 13% 15% 19% 9% 1	5510
June	1st to 10th	Day	51% 8% 12% 19% 11%	3216
	11th to 20th	Day	54% 8% 12% 18% 8%	3230
	21st to end	Day	46% 10% 16% 19% 9% 1	3230
July	1st to 10th	Day	36% 11% 23% 25% 5% 1	5296
	11th to 20th	Day	29% 9% 18% 32% 11%	5060
	21st to end	Day	42% 8% 20% 27% 3	4976
August	1st to 10th	Day	32% 10% 17% 37% 4	4702
	11th to 20th	Day	42% 11% 21% 20% 7%	4429
	21st to end	Day	45% 8% 25% 21% 2	4520
September	1st to 10th	Day	47% 9% 20% 19% 5%	2418
	11th to 20th	Day	47% 10% 21% 20% 3	2185
	21st to end	Day	48% 9% 18% 20% 6%	2071
October	1st to 10th	Day	53% 7% 12% 25% 4	3170
	11th to 20th	Day	52% 6% 15% 23% 4	2945
	21st to end	Day	52% 9% 20% 17% 1	2764
November	1st to 10th	Day	62% 8% 13% 16% 2	1551
	11th to 20th	Day	66% 9% 13% 10% 2	1272
	21st to end	Day	60% 10% 13% 12% 4	1140
December	1st to 10th	Day	63% 9% 11% 12% 4	1140
	11th to 20th	Day	59% 8% 12% 17% 3 1	1215
	21st to end	Day	40% 8% 17% 28% 7%	1738
January	1st to 10th	Night	60% 10% 15% 12% 3	5362
	11th to 20th	Night	53% 11% 16% 14% 5% 1	4827
	21st to end	Night	58% 9% 15% 13% 4	5214
February	1st to 10th	Night	54% 8% 14% 15% 9%	2798
	11th to 20th	Night	55% 7% 15% 18% 5%	2464
	21st to end	Night	50% 8% 16% 18% 7%	2041
March	1st to 10th	Night	48% 8% 17% 23% 4	3828
	11th to 20th	Night	42% 12% 14% 27% 5%	3490
	21st to end	Night	44% 8% 10% 22% 17%	3801
April	1st to 10th	Night	51% 8% 13% 17% 10% 1	1742
	11th to 20th	Night	47% 7% 12% 17% 15% 2	1691
	21st to end	Night	48% 8% 11% 23% 9% 1	1549
May	1st to 10th	Night	43% 9% 11% 25% 12% 1	2220
	11th to 20th	Night	48% 10% 13% 18% 11%	2172
	21st to end	Night	40% 12% 16% 20% 12% 1	2066
June	1st to 10th	Night	46% 9% 12% 21% 12% 1	960
	11th to 20th	Night	50% 10% 14% 17% 9%	950
	21st to end	Night	39% 10% 19% 22% 9% 1	950
July	1st to 10th	Night	31% 12% 23% 28% 5% 1	1555
	11th to 20th	Night	24% 9% 16% 40% 10% 1	1773
	21st to end	Night	35% 8% 24% 30% 3	2337
August	1st to 10th	Night	27% 9% 18% 41% 5%	2203
	11th to 20th	Night	36% 11% 24% 22% 7%	2454
	21st to end	Night	39% 9% 30% 21% 2	3146
September	1st to 10th	Night	42% 12% 21% 21% 5%	1762
	11th to 20th	Night	42% 10% 18% 24% 6%	1991
	21st to end	Night	43% 9% 18% 22% 8%	2109
October	1st to 10th	Night	47% 6% 14% 26% 7%	3800
	11th to 20th	Night	51% 7% 15% 24% 3	3981
	21st to end	Night	63% 8% 14% 13% 3	4763
November	1st to 10th	Night	62% 8% 13% 14% 4	2745
	11th to 20th	Night	62% 11% 14% 11% 2	2930
	21st to end	Night	61% 9% 15% 12% 3	3040
December	1st to 10th	Night	59% 9% 14% 13% 4	3040
	11th to 20th	Night	60% 12% 15% 10% 3	3972
	21st to end	Night	40% 10% 16% 25% 9%	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	11% 9% 33% 33% 12% 2	180
	11th to 20th	Day	12% 12% 36% 29% 9% 2	180
	21st to end	Day	7% 20% 36% 28% 8% 2	198
February	1st to 10th	Day	8% 12% 38% 27% 13% 2	180
	11th to 20th	Day	10% 12% 33% 30% 15%	240
	21st to end	Day	7% 14% 35% 28% 11% 6%	225
March	1st to 10th	Day	9% 13% 39% 24% 14% 1	362
	11th to 20th	Day	13% 17% 37% 23% 10%	460
	21st to end	Day	9% 18% 33% 28% 10% 2	506
April	1st to 10th	Day	15% 18% 38% 20% 7% 2	460
	11th to 20th	Day	17% 15% 32% 22% 10% 3	452
	21st to end	Day	16% 14% 33% 27% 8% 2	615
May	1st to 10th	Day	14% 12% 30% 26% 14% 4	653
	11th to 20th	Day	15% 11% 26% 31% 16% 1	675
	21st to end	Day	14% 12% 27% 31% 13% 3	734
June	1st to 10th	Day	21% 13% 28% 25% 11% 2	856
	11th to 20th	Day	22% 12% 26% 26% 12% 2	870
	21st to end	Day	15% 9% 24% 32% 17% 3	870
July	1st to 10th	Day	14% 7% 27% 33% 17% 2	856
	11th to 20th	Day	15% 7% 21% 31% 20% 5%	790
	21st to end	Day	17% 8% 24% 28% 18% 5%	739
August	1st to 10th	Day	14% 9% 20% 31% 19% 8%	676
	11th to 20th	Day	15% 11% 30% 28% 13% 3	605
	21st to end	Day	19% 8% 31% 27% 14% 1	539
September	1st to 10th	Day	22% 13% 31% 22% 9% 2	490
	11th to 20th	Day	19% 11% 30% 29% 8% 1	490
	21st to end	Day	19% 17% 30% 25% 9%	471
October	1st to 10th	Day	19% 17% 31% 23% 7% 3	300
	11th to 20th	Day	16% 21% 40% 19% 4	300
	21st to end	Day	18% 15% 35% 24% 6% 2	330
November	1st to 10th	Day	14% 18% 37% 22% 8%	291
	11th to 20th	Day	16% 17% 40% 21% 5% 1	182
	21st to end	Day	16% 13% 40% 24% 6% 1	180
December	1st to 10th	Day	9% 12% 36% 29% 12% 1	180
	11th to 20th	Day	11% 11% 35% 30% 11% 3	180
	21st to end	Day	4 10% 33% 37% 12% 4	198
January	1st to 10th	Night	10% 11% 38% 27% 12% 1	1040
	11th to 20th	Night	9% 12% 38% 31% 9% 1	973
	21st to end	Night	13% 13% 38% 28% 8% 1	1045
February	1st to 10th	Night	8% 10% 33% 32% 13% 4	898
	11th to 20th	Night	8% 10% 40% 30% 10% 2	744
	21st to end	Night	4 10% 36% 34% 15% 1	628
March	1st to 10th	Night	8% 11% 36% 31% 12% 2	760
	11th to 20th	Night	16% 10% 38% 28% 9% 1	760
	21st to end	Night	10% 11% 31% 33% 12% 3	821
April	1st to 10th	Night	13% 12% 35% 28% 11% 2	570
	11th to 20th	Night	12% 10% 31% 34% 12% 1	563
	21st to end	Night	15% 8% 34% 30% 11% 2	565
May	1st to 10th	Night	12% 11% 28% 32% 16% 1	380
	11th to 20th	Night	14% 11% 28% 32% 14% 1	374
	21st to end	Night	13% 8% 25% 39% 11% 4	411
June	1st to 10th	Night	22% 6% 24% 34% 14% 1	380
	11th to 20th	Night	18% 7% 28% 30% 17% 1	380
	21st to end	Night	17% 4 19% 35% 22% 3	380
July	1st to 10th	Night	11% 4 25% 38% 22% 1	370
	11th to 20th	Night	11% 4 24% 36% 22% 3	368
	21st to end	Night	13% 3 16% 36% 26% 5%	416
August	1st to 10th	Night	12% 5% 17% 37% 25% 4	378
	11th to 20th	Night	13% 4 26% 36% 20% 1	466
	21st to end	Night	19% 4 25% 33% 17% 1	627
September	1st to 10th	Night	19% 6% 28% 29% 15% 3	570
	11th to 20th	Night	19% 6% 25% 35% 13% 1	661
	21st to end	Night	16% 11% 32% 30% 11%	760
October	1st to 10th	Night	22% 11% 34% 22% 8% 2	760
	11th to 20th	Night	18% 11% 38% 22% 9% 1	760
	21st to end	Night	22% 12% 32% 24% 8% 2	1016
November	1st to 10th	Night	15% 13% 36% 25% 10% 1	975
	11th to 20th	Night	16% 11% 40% 24% 8% 1	956
	21st to end	Night	13% 15% 42% 22% 7% 1	950
December	1st to 10th	Night	10% 12% 36% 32% 10% 1	950
	11th to 20th	Night	11% 10% 39% 31% 8% 1	1031
	21st to end	Night	11% 8% 33% 31% 15% 3	1144

Page generated at 2024-11-08 20:45:35. Version ac07

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