Dawson Creek
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dawson Creek clear sky chart from 2005-11-06 to 2024-02-05.

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	10% 9% 4 7% 7% 4 6% 6% 6% 8% 33%	77201
	Night	8% 11% 4 8% 7% 4 6% 6% 6% 8% 31%	81612
Transparency	Day	48% 8% 16% 21% 7% 1	76882
	Night	49% 8% 14% 20% 8% 1	81512
Seeing	Day	16% 14% 28% 25% 14% 4	15507
	Night	15% 12% 27% 29% 15% 2	23670

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	4 12% 8% 14% 11% 7% 9% 4 5% 7% 20%	1899
	11th to 20th	Day	6% 14% 4 9% 9% 5% 8% 7% 7% 7% 24%	1978
	21st to end	Day	7% 11% 4 7% 6% 4 6% 7% 7% 9% 32%	2442
February	1st to 10th	Day	6% 13% 4 10% 8% 5% 7% 6% 7% 8% 27%	1468
	11th to 20th	Day	5% 13% 6% 11% 9% 5% 7% 5% 6% 8% 26%	1488
	21st to end	Day	5% 12% 6% 11% 8% 5% 7% 6% 6% 7% 27%	1354
March	1st to 10th	Day	6% 12% 6% 9% 10% 4 5% 5% 6% 7% 30%	1800
	11th to 20th	Day	8% 15% 5% 8% 7% 3 5% 5% 5% 7% 31%	1887
	21st to end	Day	7% 16% 6% 10% 7% 4 5% 5% 6% 8% 26%	2340
April	1st to 10th	Day	4 11% 5% 7% 8% 4 7% 7% 6% 8% 32%	2160
	11th to 20th	Day	8% 12% 5% 8% 8% 4 6% 5% 6% 7% 30%	2334
	21st to end	Day	11% 9% 4 8% 7% 5% 7% 6% 7% 8% 29%	2520
May	1st to 10th	Day	10% 8% 4 7% 7% 5% 5% 7% 8% 8% 32%	2520
	11th to 20th	Day	10% 8% 3 6% 6% 4 6% 6% 6% 8% 37%	2725
	21st to end	Day	14% 7% 3 6% 7% 4 6% 6% 7% 8% 30%	3111
June	1st to 10th	Day	13% 8% 3 6% 7% 4 6% 6% 7% 8% 33%	2880
	11th to 20th	Day	17% 9% 4 8% 7% 4 7% 6% 6% 8% 26%	2880
	21st to end	Day	10% 6% 2 6% 7% 4 6% 7% 8% 9% 35%	2880
July	1st to 10th	Day	13% 6% 2 6% 6% 4 6% 6% 7% 8% 37%	2880
	11th to 20th	Day	12% 6% 3 6% 6% 4 7% 6% 7% 9% 34%	2880
	21st to end	Day	10% 5% 3 5% 5% 3 5% 6% 7% 8% 40%	3027
August	1st to 10th	Day	11% 5% 3 6% 5% 4 6% 6% 6% 9% 38%	2549
	11th to 20th	Day	11% 5% 1 5% 5% 3 5% 5% 7% 11% 42%	2475
	21st to end	Day	11% 6% 3 6% 7% 4 5% 5% 7% 7% 38%	2638
September	1st to 10th	Day	13% 6% 3 6% 6% 3 5% 5% 6% 8% 40%	2160
	11th to 20th	Day	12% 6% 3 5% 5% 3 4 5% 6% 9% 41%	2160
	21st to end	Day	10% 8% 2 6% 6% 4 7% 6% 6% 9% 37%	1925
October	1st to 10th	Day	13% 12% 4 8% 7% 3 5% 3 5% 6% 34%	1800
	11th to 20th	Day	11% 10% 4 6% 7% 4 6% 5% 5% 9% 32%	1688
	21st to end	Day	11% 13% 5% 8% 6% 3 4 5% 5% 6% 34%	1688
November	1st to 10th	Day	14% 12% 5% 10% 6% 4 3 4 5% 7% 30%	1455
	11th to 20th	Day	9% 13% 7% 8% 7% 3 6% 4 6% 7% 29%	1330
	21st to end	Day	9% 12% 5% 10% 8% 5% 5% 4 7% 7% 29%	1208
December	1st to 10th	Day	8% 16% 4 6% 7% 4 6% 6% 6% 7% 31%	1140
	11th to 20th	Day	10% 11% 5% 9% 8% 5% 6% 5% 6% 8% 25%	1442
	21st to end	Day	4 9% 3 7% 7% 4 5% 7% 8% 8% 39%	2090
January	1st to 10th	Night	5% 15% 6% 13% 11% 4 6% 6% 6% 6% 23%	5046
	11th to 20th	Night	5% 10% 4 8% 9% 5% 7% 9% 11% 8% 24%	4952
	21st to end	Night	10% 15% 5% 7% 6% 4 6% 6% 6% 9% 27%	5214
February	1st to 10th	Night	7% 14% 6% 9% 8% 6% 6% 5% 5% 9% 26%	2585
	11th to 20th	Night	6% 14% 6% 10% 9% 4 5% 6% 7% 8% 24%	2358
	21st to end	Night	3 11% 6% 10% 8% 5% 9% 5% 6% 7% 28%	1902
March	1st to 10th	Night	5% 10% 5% 11% 8% 4 6% 6% 6% 7% 32%	2160
	11th to 20th	Night	7% 13% 6% 9% 7% 4 6% 5% 5% 8% 30%	2069
	21st to end	Night	8% 14% 4 7% 7% 4 6% 5% 6% 8% 31%	2016
April	1st to 10th	Night	4 8% 4 9% 9% 5% 7% 7% 6% 9% 30%	1800
	11th to 20th	Night	8% 11% 4 8% 7% 4 6% 6% 7% 9% 31%	1572
	21st to end	Night	12% 9% 5% 8% 6% 3 5% 5% 6% 6% 35%	1440
May	1st to 10th	Night	10% 8% 4 9% 8% 5% 6% 6% 5% 7% 34%	1440
	11th to 20th	Night	11% 7% 3 5% 6% 3 5% 5% 6% 7% 41%	1167
	21st to end	Night	13% 7% 4 7% 6% 4 4 6% 7% 9% 33%	1164
June	1st to 10th	Night	12% 8% 4 8% 6% 4 6% 6% 6% 7% 33%	1080
	11th to 20th	Night	16% 8% 4 8% 9% 3 4 6% 6% 8% 28%	1080
	21st to end	Night	11% 6% 3 6% 5% 4 6% 6% 5% 8% 40%	1080
July	1st to 10th	Night	12% 5% 2 5% 5% 3 7% 7% 7% 8% 39%	1080
	11th to 20th	Night	11% 5% 3 6% 5% 3 6% 8% 9% 8% 36%	1080
	21st to end	Night	9% 3 2 5% 6% 4 6% 5% 8% 10% 43%	1288
August	1st to 10th	Night	9% 3 2 4 6% 4 5% 8% 9% 8% 41%	1389
	11th to 20th	Night	8% 4 2 5% 6% 3 5% 5% 7% 9% 45%	1424
	21st to end	Night	12% 6% 2 6% 6% 3 6% 5% 7% 9% 38%	1715
September	1st to 10th	Night	14% 7% 3 6% 5% 3 5% 4 7% 7% 40%	1800
	11th to 20th	Night	12% 6% 3 6% 5% 4 3 5% 5% 8% 43%	1800
	21st to end	Night	10% 7% 3 7% 7% 3 5% 5% 6% 7% 39%	2034
October	1st to 10th	Night	11% 12% 3 7% 5% 4 4 5% 6% 8% 34%	2160
	11th to 20th	Night	11% 9% 3 8% 7% 5% 5% 5% 6% 8% 34%	2272
	21st to end	Night	12% 13% 5% 7% 6% 3 4 6% 6% 6% 32%	2667
November	1st to 10th	Night	13% 12% 6% 9% 7% 3 5% 4 5% 7% 29%	2604
	11th to 20th	Night	8% 15% 5% 10% 7% 4 5% 5% 5% 7% 29%	2850
	21st to end	Night	7% 11% 6% 11% 9% 4 5% 5% 6% 7% 29%	2968
December	1st to 10th	Night	7% 11% 5% 8% 8% 5% 5% 5% 6% 7% 31%	3040
	11th to 20th	Night	8% 16% 5% 9% 7% 5% 7% 6% 6% 6% 26%	3750
	21st to end	Night	4 9% 4 8% 7% 4 6% 6% 7% 9% 35%	5566

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% 7% 10% 16% 4	1899
	11th to 20th	Day	57% 6% 11% 11% 13% 2	1996
	21st to end	Day	43% 12% 23% 17% 5% 1	2442
February	1st to 10th	Day	53% 8% 13% 14% 11% 1	1468
	11th to 20th	Day	55% 8% 15% 16% 6%	1496
	21st to end	Day	56% 8% 11% 18% 7% 1	1354
March	1st to 10th	Day	53% 5% 14% 18% 10% 1	1800
	11th to 20th	Day	51% 7% 14% 20% 8% 1	1887
	21st to end	Day	56% 7% 15% 17% 5%	2340
April	1st to 10th	Day	47% 9% 14% 19% 9%	2160
	11th to 20th	Day	53% 7% 13% 19% 8%	2334
	21st to end	Day	52% 8% 11% 21% 7% 1	2520
May	1st to 10th	Day	47% 8% 14% 21% 9% 1	2520
	11th to 20th	Day	44% 6% 13% 23% 12% 2	2729
	21st to end	Day	50% 8% 12% 21% 8% 2	3112
June	1st to 10th	Day	46% 9% 13% 22% 9% 1	2880
	11th to 20th	Day	55% 7% 10% 19% 7%	2880
	21st to end	Day	42% 9% 15% 24% 10%	2880
July	1st to 10th	Day	42% 9% 16% 23% 10% 1	2801
	11th to 20th	Day	45% 10% 19% 22% 4	2793
	21st to end	Day	36% 10% 21% 26% 5%	2859
August	1st to 10th	Day	41% 10% 22% 23% 4	2531
	11th to 20th	Day	36% 7% 22% 28% 7%	2475
	21st to end	Day	43% 8% 18% 25% 6%	2638
September	1st to 10th	Day	42% 7% 22% 24% 5% 1	2160
	11th to 20th	Day	39% 8% 19% 28% 6%	2160
	21st to end	Day	42% 10% 17% 23% 8% 1	1925
October	1st to 10th	Day	51% 6% 14% 23% 5% 1	1800
	11th to 20th	Day	48% 7% 17% 24% 5%	1688
	21st to end	Day	50% 6% 18% 19% 7%	1688
November	1st to 10th	Day	54% 6% 14% 20% 5% 1	1455
	11th to 20th	Day	53% 7% 17% 16% 7%	1330
	21st to end	Day	54% 6% 13% 18% 7% 1	1208
December	1st to 10th	Day	51% 8% 14% 16% 10% 2	1140
	11th to 20th	Day	56% 7% 13% 18% 5%	1444
	21st to end	Day	39% 7% 17% 23% 11% 2	2090
January	1st to 10th	Night	59% 7% 11% 16% 6% 1	5046
	11th to 20th	Night	51% 7% 13% 12% 16% 1	4996
	21st to end	Night	51% 10% 16% 16% 5%	5214
February	1st to 10th	Night	55% 6% 13% 16% 9% 1	2585
	11th to 20th	Night	55% 8% 13% 20% 5%	2360
	21st to end	Night	53% 6% 13% 18% 8% 1	1902
March	1st to 10th	Night	50% 5% 14% 22% 8% 1	2160
	11th to 20th	Night	51% 7% 13% 22% 7%	2070
	21st to end	Night	50% 7% 14% 21% 8%	2016
April	1st to 10th	Night	48% 7% 14% 20% 11% 1	1800
	11th to 20th	Night	48% 5% 13% 23% 9% 1	1572
	21st to end	Night	48% 8% 10% 23% 10% 2	1440
May	1st to 10th	Night	47% 8% 13% 20% 11% 1	1440
	11th to 20th	Night	40% 7% 12% 25% 15% 1	1167
	21st to end	Night	46% 7% 13% 23% 10% 1	1164
June	1st to 10th	Night	48% 7% 11% 24% 10%	1080
	11th to 20th	Night	52% 8% 11% 22% 6% 1	1080
	21st to end	Night	39% 9% 17% 23% 11% 1	1080
July	1st to 10th	Night	38% 10% 16% 27% 9% 1	1050
	11th to 20th	Night	39% 12% 21% 24% 4	1044
	21st to end	Night	32% 11% 23% 30% 4	1217
August	1st to 10th	Night	35% 12% 21% 25% 8%	1382
	11th to 20th	Night	33% 9% 18% 31% 8% 1	1424
	21st to end	Night	41% 9% 19% 25% 6% 1	1715
September	1st to 10th	Night	41% 8% 19% 23% 7% 1	1800
	11th to 20th	Night	39% 7% 17% 31% 6%	1800
	21st to end	Night	42% 9% 16% 22% 11% 1	2034
October	1st to 10th	Night	48% 8% 16% 21% 6% 1	2160
	11th to 20th	Night	46% 9% 16% 24% 5%	2272
	21st to end	Night	50% 7% 15% 20% 8%	2667
November	1st to 10th	Night	54% 7% 12% 21% 5% 1	2604
	11th to 20th	Night	55% 7% 13% 18% 7%	2850
	21st to end	Night	53% 6% 13% 20% 6% 1	2968
December	1st to 10th	Night	51% 8% 12% 18% 11% 1	3040
	11th to 20th	Night	56% 7% 12% 17% 7%	3747
	21st to end	Night	44% 8% 16% 23% 8% 2	5566

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	13% 10% 31% 29% 11% 6%	180
	11th to 20th	Day	17% 14% 31% 26% 10% 2	180
	21st to end	Day	16% 17% 28% 20% 15% 4	198
February	1st to 10th	Day	17% 13% 32% 24% 13% 2	168
	11th to 20th	Day	16% 17% 29% 24% 12% 2	248
	21st to end	Day	13% 15% 35% 24% 12% 1	290
March	1st to 10th	Day	13% 18% 26% 25% 13% 4	420
	11th to 20th	Day	12% 15% 34% 25% 11% 2	420
	21st to end	Day	19% 15% 27% 24% 13% 1	462
April	1st to 10th	Day	11% 18% 35% 23% 10% 3	420
	11th to 20th	Day	17% 18% 28% 22% 12% 4	412
	21st to end	Day	18% 17% 32% 19% 11% 2	420
May	1st to 10th	Day	17% 17% 33% 23% 8% 2	423
	11th to 20th	Day	14% 12% 24% 29% 18% 4	694
	21st to end	Day	15% 13% 22% 29% 18% 3	874
June	1st to 10th	Day	16% 15% 30% 22% 14% 2	810
	11th to 20th	Day	20% 11% 25% 25% 16% 3	810
	21st to end	Day	13% 10% 25% 25% 20% 7%	810
July	1st to 10th	Day	14% 9% 26% 28% 19% 4	796
	11th to 20th	Day	13% 8% 28% 26% 19% 6%	792
	21st to end	Day	12% 10% 28% 29% 16% 5%	773
August	1st to 10th	Day	14% 12% 20% 29% 18% 6%	489
	11th to 20th	Day	14% 17% 29% 22% 14% 5%	437
	21st to end	Day	15% 16% 30% 20% 13% 6%	495
September	1st to 10th	Day	19% 12% 30% 19% 15% 5%	450
	11th to 20th	Day	19% 14% 28% 24% 10% 5%	450
	21st to end	Day	13% 25% 29% 22% 11% 1	450
October	1st to 10th	Day	26% 14% 26% 19% 11% 4	450
	11th to 20th	Day	17% 15% 32% 23% 11% 1	338
	21st to end	Day	20% 16% 26% 24% 11% 3	250
November	1st to 10th	Day	21% 15% 31% 21% 11% 2	180
	11th to 20th	Day	19% 16% 32% 25% 6% 2	180
	21st to end	Day	21% 18% 24% 24% 9% 3	180
December	1st to 10th	Day	9% 24% 28% 27% 9% 3	180
	11th to 20th	Day	16% 16% 21% 31% 17%	180
	21st to end	Day	12% 13% 26% 28% 18% 4	198
January	1st to 10th	Night	13% 12% 28% 32% 14% 2	1040
	11th to 20th	Night	14% 17% 25% 31% 11% 1	1002
	21st to end	Night	20% 18% 28% 25% 8% 1	935
February	1st to 10th	Night	17% 15% 21% 27% 17% 4	739
	11th to 20th	Night	13% 14% 28% 29% 14% 2	704
	21st to end	Night	7% 12% 31% 29% 19% 3	592
March	1st to 10th	Night	9% 14% 25% 32% 17% 3	720
	11th to 20th	Night	12% 10% 31% 32% 14% 2	720
	21st to end	Night	13% 9% 24% 30% 21% 3	792
April	1st to 10th	Night	9% 10% 29% 31% 18% 4	720
	11th to 20th	Night	12% 11% 31% 29% 15% 3	504
	21st to end	Night	16% 14% 28% 26% 15% 1	360
May	1st to 10th	Night	13% 14% 27% 32% 13% 3	360
	11th to 20th	Night	13% 9% 25% 31% 20% 2	354
	21st to end	Night	16% 8% 23% 28% 22% 3	389
June	1st to 10th	Night	14% 8% 27% 31% 18% 2	360
	11th to 20th	Night	19% 6% 23% 30% 18% 4	360
	21st to end	Night	14% 7% 23% 33% 20% 3	360
July	1st to 10th	Night	15% 7% 22% 34% 22% 1	350
	11th to 20th	Night	13% 6% 26% 29% 22% 5%	348
	21st to end	Night	9% 7% 24% 37% 21% 3	394
August	1st to 10th	Night	10% 4 20% 30% 29% 6%	358
	11th to 20th	Night	10% 10% 26% 31% 21% 2	356
	21st to end	Night	14% 7% 28% 29% 20% 2	527
September	1st to 10th	Night	18% 9% 21% 33% 16% 3	720
	11th to 20th	Night	16% 8% 24% 30% 21% 3	720
	21st to end	Night	15% 18% 28% 26% 11% 3	720
October	1st to 10th	Night	20% 13% 25% 28% 13% 1	720
	11th to 20th	Night	16% 14% 30% 27% 11% 1	720
	21st to end	Night	21% 15% 31% 24% 7% 1	792
November	1st to 10th	Night	20% 13% 28% 25% 13% 2	754
	11th to 20th	Night	17% 17% 30% 27% 8% 1	950
	21st to end	Night	15% 16% 32% 27% 9% 1	1006
December	1st to 10th	Night	14% 15% 32% 28% 10% 1	1040
	11th to 20th	Night	15% 15% 29% 25% 14% 2	1040
	21st to end	Night	13% 12% 26% 34% 13% 2	1144

Page generated at 2024-02-02 03:20:32. Version ac07

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