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 2024-01-14.

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% 10% 4 8% 7% 4 6% 6% 6% 7% 31%	74486
	Night	9% 10% 5% 9% 8% 5% 6% 6% 6% 7% 29%	75260
Transparency	Day	50% 9% 15% 19% 6%	74144
	Night	51% 9% 15% 18% 6%	75120
Seeing	Day	16% 12% 30% 27% 13% 3	15267
	Night	14% 9% 33% 30% 12% 2	23850

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% 13% 5% 12% 10% 6% 8% 7% 8% 6% 18%	949
	11th to 20th	Day	5% 14% 6% 13% 9% 3 8% 7% 8% 7% 20%	1231
	21st to end	Day	4 12% 7% 13% 11% 6% 8% 7% 7% 5% 20%	1386
February	1st to 10th	Day	4 9% 5% 10% 9% 6% 12% 9% 7% 9% 21%	1325
	11th to 20th	Day	5% 10% 5% 12% 7% 7% 8% 8% 5% 5% 27%	1518
	21st to end	Day	2 7% 6% 10% 10% 7% 9% 8% 8% 7% 25%	1332
March	1st to 10th	Day	4 10% 5% 10% 10% 5% 9% 6% 7% 8% 28%	1738
	11th to 20th	Day	8% 13% 7% 10% 7% 3 6% 5% 5% 6% 29%	1979
	21st to end	Day	4 10% 6% 9% 8% 4 6% 5% 7% 8% 35%	2192
April	1st to 10th	Day	8% 12% 5% 10% 8% 3 6% 6% 5% 6% 31%	2308
	11th to 20th	Day	8% 11% 4 9% 9% 4 6% 5% 6% 6% 30%	2310
	21st to end	Day	10% 12% 5% 10% 8% 4 6% 6% 6% 8% 27%	2489
May	1st to 10th	Day	10% 10% 5% 8% 7% 5% 5% 5% 5% 6% 34%	2700
	11th to 20th	Day	10% 8% 3 6% 6% 4 5% 5% 5% 8% 39%	2666
	21st to end	Day	13% 6% 3 5% 5% 3 5% 5% 6% 8% 41%	3111
June	1st to 10th	Day	14% 8% 3 7% 7% 3 6% 6% 6% 8% 31%	3046
	11th to 20th	Day	18% 10% 4 7% 7% 4 5% 5% 6% 7% 28%	3060
	21st to end	Day	15% 7% 4 6% 6% 4 6% 6% 6% 8% 31%	3060
July	1st to 10th	Day	15% 6% 2 6% 6% 4 6% 6% 7% 8% 34%	3060
	11th to 20th	Day	13% 7% 3 6% 6% 4 6% 6% 7% 10% 33%	2945
	21st to end	Day	14% 7% 3 7% 6% 4 6% 5% 7% 9% 32%	2938
August	1st to 10th	Day	15% 7% 3 6% 5% 3 5% 5% 5% 8% 37%	2686
	11th to 20th	Day	16% 7% 3 5% 6% 4 6% 4 6% 8% 35%	2513
	21st to end	Day	20% 7% 3 6% 5% 4 5% 5% 5% 7% 32%	2574
September	1st to 10th	Day	19% 9% 3 6% 5% 3 5% 4 4 7% 35%	2291
	11th to 20th	Day	14% 10% 4 6% 5% 4 5% 6% 6% 8% 32%	2070
	21st to end	Day	12% 10% 4 7% 5% 4 5% 5% 6% 7% 34%	1962
October	1st to 10th	Day	14% 16% 6% 8% 5% 3 4 5% 5% 7% 28%	1800
	11th to 20th	Day	9% 13% 6% 10% 7% 4 3 4 4 7% 32%	1684
	21st to end	Day	11% 16% 7% 12% 7% 3 3 4 4 6% 26%	1594
November	1st to 10th	Day	9% 16% 7% 11% 11% 4 5% 4 4 5% 24%	1472
	11th to 20th	Day	10% 12% 5% 13% 14% 5% 6% 5% 5% 6% 19%	1265
	21st to end	Day	9% 11% 6% 14% 10% 4 7% 6% 4 6% 22%	1140
December	1st to 10th	Day	5% 11% 7% 11% 12% 7% 9% 7% 6% 6% 19%	1140
	11th to 20th	Day	8% 13% 4 13% 10% 4 6% 6% 4 6% 25%	1214
	21st to end	Day	4 7% 4 8% 7% 5% 6% 7% 6% 7% 40%	1738
January	1st to 10th	Night	6% 11% 5% 11% 10% 5% 8% 8% 7% 6% 23%	3212
	11th to 20th	Night	5% 11% 7% 12% 9% 5% 8% 8% 9% 7% 19%	2800
	21st to end	Night	6% 12% 6% 13% 9% 6% 8% 6% 6% 5% 22%	2970
February	1st to 10th	Night	4 9% 5% 8% 9% 7% 11% 9% 8% 6% 25%	2650
	11th to 20th	Night	4 11% 6% 10% 9% 6% 8% 7% 7% 6% 25%	2329
	21st to end	Night	2 7% 5% 13% 12% 5% 8% 7% 8% 7% 27%	1924
March	1st to 10th	Night	5% 10% 6% 11% 10% 5% 6% 6% 7% 7% 30%	2219
	11th to 20th	Night	9% 14% 6% 8% 6% 4 5% 5% 5% 7% 29%	1980
	21st to end	Night	6% 10% 5% 8% 7% 4 6% 6% 7% 8% 33%	2164
April	1st to 10th	Night	10% 10% 4 11% 7% 4 5% 5% 6% 7% 30%	1651
	11th to 20th	Night	7% 9% 5% 9% 7% 4 7% 5% 7% 7% 33%	1601
	21st to end	Night	8% 12% 5% 9% 7% 4 5% 5% 6% 6% 32%	1469
May	1st to 10th	Night	10% 9% 5% 6% 5% 4 4 5% 7% 8% 36%	1260
	11th to 20th	Night	12% 8% 3 5% 4 4 5% 5% 7% 9% 39%	1226
	21st to end	Night	10% 7% 4 6% 5% 3 5% 6% 7% 7% 40%	1164
June	1st to 10th	Night	17% 6% 2 6% 5% 3 5% 6% 7% 9% 33%	910
	11th to 20th	Night	18% 9% 4 5% 7% 5% 4 6% 6% 6% 31%	900
	21st to end	Night	15% 6% 1 5% 7% 4 5% 6% 7% 9% 37%	900
July	1st to 10th	Night	9% 5% 2 6% 5% 3 5% 7% 8% 10% 39%	900
	11th to 20th	Night	11% 5% 2 5% 7% 3 5% 7% 7% 9% 38%	1011
	21st to end	Night	11% 4 2 5% 6% 3 4 5% 7% 12% 41%	1379
August	1st to 10th	Night	13% 5% 2 5% 4 4 5% 6% 6% 9% 41%	1253
	11th to 20th	Night	11% 7% 2 5% 5% 3 5% 6% 7% 9% 39%	1385
	21st to end	Night	15% 7% 3 6% 7% 3 5% 5% 5% 7% 37%	1782
September	1st to 10th	Night	16% 9% 3 5% 5% 3 4 5% 6% 8% 36%	1669
	11th to 20th	Night	15% 7% 2 5% 5% 3 5% 5% 7% 7% 37%	1886
	21st to end	Night	13% 9% 2 6% 5% 4 4 5% 7% 7% 38%	1998
October	1st to 10th	Night	15% 14% 4 7% 5% 3 4 4 4 6% 33%	2160
	11th to 20th	Night	11% 14% 5% 10% 6% 3 5% 4 5% 6% 30%	2274
	21st to end	Night	10% 19% 8% 12% 8% 5% 5% 4 5% 5% 20%	2744
November	1st to 10th	Night	10% 13% 7% 13% 10% 4 4 4 5% 5% 25%	2604
	11th to 20th	Night	10% 12% 5% 12% 13% 5% 6% 6% 6% 6% 21%	2914
	21st to end	Night	8% 12% 7% 13% 10% 5% 7% 6% 6% 5% 23%	3040
December	1st to 10th	Night	5% 10% 5% 10% 12% 7% 8% 7% 6% 8% 22%	3040
	11th to 20th	Night	7% 13% 6% 11% 10% 6% 9% 8% 6% 7% 18%	3974
	21st to end	Night	3 8% 3 8% 8% 5% 6% 7% 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	62% 9% 12% 12% 5%	949
	11th to 20th	Day	60% 10% 12% 14% 4 1	1231
	21st to end	Day	61% 9% 11% 12% 7%	1386
February	1st to 10th	Day	55% 8% 13% 15% 9%	1325
	11th to 20th	Day	55% 7% 16% 17% 5%	1527
	21st to end	Day	52% 8% 13% 20% 7%	1332
March	1st to 10th	Day	51% 8% 15% 20% 4 1	1738
	11th to 20th	Day	53% 8% 13% 21% 5%	1980
	21st to end	Day	45% 8% 14% 26% 6%	2192
April	1st to 10th	Day	51% 8% 12% 18% 10% 1	2308
	11th to 20th	Day	52% 6% 11% 20% 11% 1	2310
	21st to end	Day	52% 8% 11% 22% 7%	2489
May	1st to 10th	Day	48% 6% 11% 22% 12% 1	2700
	11th to 20th	Day	42% 7% 12% 22% 16% 1	2670
	21st to end	Day	39% 8% 13% 23% 16% 1	3112
June	1st to 10th	Day	49% 8% 12% 20% 11%	3046
	11th to 20th	Day	53% 8% 12% 18% 8%	3060
	21st to end	Day	48% 10% 17% 18% 7% 1	3060
July	1st to 10th	Day	44% 11% 18% 20% 7% 1	2976
	11th to 20th	Day	44% 12% 22% 20% 2	2852
	21st to end	Day	46% 10% 20% 21% 2	2775
August	1st to 10th	Day	42% 11% 22% 22% 3	2668
	11th to 20th	Day	44% 12% 23% 17% 4	2513
	21st to end	Day	50% 9% 19% 19% 2	2574
September	1st to 10th	Day	48% 9% 20% 18% 5%	2291
	11th to 20th	Day	47% 10% 20% 20% 3	2070
	21st to end	Day	47% 9% 18% 20% 6%	1962
October	1st to 10th	Day	56% 7% 15% 19% 3	1800
	11th to 20th	Day	52% 8% 14% 20% 5%	1684
	21st to end	Day	59% 9% 15% 14% 2	1594
November	1st to 10th	Day	63% 8% 12% 15% 2	1472
	11th to 20th	Day	66% 9% 13% 10% 2	1265
	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	57% 9% 16% 14% 4	3212
	11th to 20th	Night	59% 10% 13% 14% 3 1	2800
	21st to end	Night	61% 8% 12% 12% 7%	2970
February	1st to 10th	Night	54% 8% 14% 14% 9%	2650
	11th to 20th	Night	56% 7% 16% 16% 4	2330
	21st to end	Night	51% 8% 16% 18% 7%	1924
March	1st to 10th	Night	51% 7% 16% 21% 5%	2219
	11th to 20th	Night	54% 7% 12% 21% 6%	1980
	21st to end	Night	46% 9% 13% 23% 8%	2164
April	1st to 10th	Night	50% 8% 13% 18% 10% 1	1651
	11th to 20th	Night	48% 7% 12% 17% 14% 2	1601
	21st to end	Night	49% 8% 11% 23% 9% 1	1469
May	1st to 10th	Night	43% 6% 12% 25% 13% 1	1260
	11th to 20th	Night	39% 8% 12% 22% 19% 1	1226
	21st to end	Night	40% 7% 12% 19% 20% 1	1164
June	1st to 10th	Night	44% 9% 12% 22% 13% 1	910
	11th to 20th	Night	50% 10% 13% 18% 9%	900
	21st to end	Night	40% 10% 19% 22% 8%	900
July	1st to 10th	Night	35% 12% 19% 27% 6% 1	875
	11th to 20th	Night	36% 14% 24% 24% 1	981
	21st to end	Night	35% 10% 28% 24% 4	1302
August	1st to 10th	Night	37% 10% 24% 26% 4	1246
	11th to 20th	Night	37% 12% 24% 22% 4	1385
	21st to end	Night	44% 11% 21% 21% 3	1782
September	1st to 10th	Night	42% 12% 21% 20% 5%	1669
	11th to 20th	Night	43% 10% 17% 23% 6%	1886
	21st to end	Night	43% 9% 18% 22% 9%	1998
October	1st to 10th	Night	53% 7% 14% 21% 5% 1	2160
	11th to 20th	Night	53% 8% 18% 18% 3	2274
	21st to end	Night	65% 8% 13% 10% 4	2744
November	1st to 10th	Night	62% 7% 13% 14% 3	2604
	11th to 20th	Night	62% 11% 14% 11% 2	2914
	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	13% 12% 37% 28% 7% 3	166
	21st to end	Day	7% 18% 36% 28% 9% 2	176
February	1st to 10th	Day	9% 11% 39% 28% 12% 1	160
	11th to 20th	Day	11% 13% 33% 27% 16%	214
	21st to end	Day	6% 14% 33% 30% 12% 7%	198
March	1st to 10th	Day	9% 12% 39% 24% 15% 1	327
	11th to 20th	Day	13% 16% 38% 23% 10%	420
	21st to end	Day	10% 17% 34% 27% 10% 1	462
April	1st to 10th	Day	14% 17% 38% 21% 7% 3	420
	11th to 20th	Day	17% 14% 33% 22% 10% 3	412
	21st to end	Day	16% 15% 34% 26% 7% 2	566
May	1st to 10th	Day	14% 11% 30% 27% 15% 3	603
	11th to 20th	Day	13% 11% 27% 33% 16% 1	625
	21st to end	Day	14% 12% 27% 31% 13% 3	679
June	1st to 10th	Day	19% 12% 28% 26% 12% 2	796
	11th to 20th	Day	23% 12% 26% 26% 12% 2	810
	21st to end	Day	16% 8% 25% 31% 17% 3	810
July	1st to 10th	Day	15% 8% 27% 31% 16% 3	796
	11th to 20th	Day	16% 7% 22% 31% 20% 5%	734
	21st to end	Day	16% 8% 24% 27% 19% 5%	684
August	1st to 10th	Day	15% 8% 19% 31% 19% 8%	626
	11th to 20th	Day	15% 11% 29% 28% 14% 3	559
	21st to end	Day	20% 7% 29% 28% 14% 2	495
September	1st to 10th	Day	24% 13% 29% 22% 10% 2	450
	11th to 20th	Day	20% 12% 30% 28% 8% 1	450
	21st to end	Day	19% 16% 30% 26% 9%	432
October	1st to 10th	Day	20% 17% 30% 22% 7% 4	270
	11th to 20th	Day	16% 21% 39% 19% 4	270
	21st to end	Day	19% 13% 34% 25% 7% 2	297
November	1st to 10th	Day	15% 17% 37% 23% 7%	262
	11th to 20th	Day	16% 17% 39% 22% 5% 1	180
	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% 32% 9% 1	941
	21st to end	Night	13% 13% 37% 28% 8% 1	990
February	1st to 10th	Night	8% 11% 33% 32% 13% 4	850
	11th to 20th	Night	9% 10% 39% 30% 10% 2	704
	21st to end	Night	4 9% 36% 35% 15% 1	592
March	1st to 10th	Night	8% 10% 36% 31% 13% 2	720
	11th to 20th	Night	17% 9% 37% 28% 9% 1	720
	21st to end	Night	10% 11% 31% 33% 12% 3	778
April	1st to 10th	Night	13% 11% 34% 28% 12% 2	540
	11th to 20th	Night	12% 9% 31% 33% 13% 1	533
	21st to end	Night	15% 7% 35% 29% 11% 2	536
May	1st to 10th	Night	12% 11% 28% 32% 16% 1	360
	11th to 20th	Night	13% 10% 29% 32% 15% 1	354
	21st to end	Night	13% 6% 26% 39% 11% 4	389
June	1st to 10th	Night	21% 6% 24% 35% 14% 1	360
	11th to 20th	Night	18% 6% 28% 30% 18% 1	360
	21st to end	Night	18% 5% 19% 33% 22% 4	360
July	1st to 10th	Night	11% 5% 24% 38% 21% 1	350
	11th to 20th	Night	11% 4 24% 35% 22% 3	348
	21st to end	Night	13% 3 16% 36% 27% 6%	394
August	1st to 10th	Night	13% 5% 17% 36% 25% 4	358
	11th to 20th	Night	13% 4 26% 36% 20% 1	441
	21st to end	Night	19% 4 25% 32% 18% 2	594
September	1st to 10th	Night	19% 6% 26% 29% 16% 3	540
	11th to 20th	Night	19% 6% 25% 35% 13% 1	626
	21st to end	Night	16% 10% 32% 30% 11%	720
October	1st to 10th	Night	22% 11% 34% 22% 9% 2	720
	11th to 20th	Night	19% 10% 38% 23% 9% 2	720
	21st to end	Night	21% 12% 32% 24% 9% 2	962
November	1st to 10th	Night	16% 12% 36% 26% 10% 1	925
	11th to 20th	Night	16% 11% 40% 23% 9% 1	950
	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 2024-01-11 02:22:42. Version ac07

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