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 2025-02-06.

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 9% 6% 5% 6% 4 7% 8% 34%	111382
	Night	7% 11% 4 10% 6% 6% 6% 4 6% 7% 32%	115491
Transparency	Day	46% 6% 15% 22% 9% 1	111105
	Night	49% 6% 14% 21% 9% 1	115415
Seeing	Day	15% 14% 28% 25% 14% 4	16877
	Night	14% 12% 27% 30% 15% 2	25003

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 13% 6% 15% 8% 8% 7% 4 5% 8% 23%	2719
	11th to 20th	Day	5% 14% 4 10% 6% 8% 9% 5% 8% 8% 24%	2840
	21st to end	Day	5% 10% 5% 10% 6% 5% 6% 5% 7% 9% 33%	3498
February	1st to 10th	Day	6% 13% 3 11% 6% 7% 6% 5% 7% 8% 27%	1556
	11th to 20th	Day	5% 14% 4 12% 7% 6% 6% 4 6% 8% 28%	1573
	21st to end	Day	5% 13% 5% 13% 8% 6% 6% 4 6% 7% 27%	1437
March	1st to 10th	Day	3 9% 4 13% 11% 9% 6% 4 6% 8% 27%	3138
	11th to 20th	Day	7% 14% 4 8% 5% 5% 5% 4 7% 8% 31%	3332
	21st to end	Day	4 12% 5% 12% 6% 5% 5% 4 7% 8% 30%	4103
April	1st to 10th	Day	4 12% 4 8% 7% 6% 7% 6% 6% 8% 32%	2280
	11th to 20th	Day	8% 13% 5% 9% 6% 5% 6% 4 5% 7% 31%	2467
	21st to end	Day	10% 10% 4 9% 6% 7% 6% 5% 7% 8% 28%	2660
May	1st to 10th	Day	7% 9% 3 7% 6% 6% 5% 5% 9% 8% 34%	4420
	11th to 20th	Day	7% 10% 3 9% 6% 6% 7% 5% 6% 8% 32%	4835
	21st to end	Day	11% 10% 3 11% 7% 6% 6% 5% 7% 8% 26%	5509
June	1st to 10th	Day	12% 9% 3 7% 7% 5% 5% 5% 7% 8% 32%	3040
	11th to 20th	Day	16% 10% 4 9% 6% 6% 6% 4 6% 8% 25%	3040
	21st to end	Day	11% 7% 2 8% 6% 5% 6% 5% 8% 9% 34%	3040
July	1st to 10th	Day	12% 5% 2 5% 4 4 4 4 6% 7% 48%	5060
	11th to 20th	Day	8% 5% 2 5% 4 4 5% 4 6% 7% 49%	5060
	21st to end	Day	10% 6% 2 6% 5% 5% 5% 5% 7% 8% 41%	5283
August	1st to 10th	Day	9% 5% 2 5% 4 4 5% 3 5% 7% 49%	4470
	11th to 20th	Day	12% 6% 2 7% 5% 5% 5% 4 7% 9% 38%	4330
	21st to end	Day	12% 6% 2 6% 5% 4 5% 4 7% 9% 40%	4624
September	1st to 10th	Day	13% 6% 3 7% 5% 4 4 4 6% 8% 40%	2280
	11th to 20th	Day	12% 7% 2 6% 5% 5% 4 4 6% 9% 40%	2280
	21st to end	Day	10% 9% 2 7% 5% 6% 6% 4 6% 9% 36%	2031
October	1st to 10th	Day	13% 12% 3 8% 5% 5% 5% 4 7% 7% 31%	3180
	11th to 20th	Day	10% 10% 3 8% 5% 5% 6% 5% 6% 8% 33%	2952
	21st to end	Day	9% 12% 4 9% 4 3 5% 5% 6% 8% 35%	2927
November	1st to 10th	Day	14% 13% 5% 11% 5% 4 4 3 6% 7% 30%	1533
	11th to 20th	Day	9% 16% 6% 10% 7% 4 5% 3 6% 7% 28%	1400
	21st to end	Day	8% 14% 4 12% 7% 5% 5% 3 7% 7% 28%	1271
December	1st to 10th	Day	10% 20% 4 10% 6% 5% 6% 4 6% 6% 22%	1960
	11th to 20th	Day	8% 14% 5% 11% 8% 9% 7% 5% 6% 8% 19%	2262
	21st to end	Day	3 8% 3 9% 6% 5% 5% 5% 8% 8% 41%	2992
January	1st to 10th	Night	3 13% 5% 14% 9% 6% 6% 5% 6% 6% 26%	7226
	11th to 20th	Night	4 10% 5% 11% 8% 7% 6% 6% 9% 8% 25%	7090
	21st to end	Night	8% 14% 5% 8% 5% 5% 5% 4 5% 8% 31%	7458
February	1st to 10th	Night	6% 16% 5% 10% 7% 8% 5% 4 6% 8% 26%	2733
	11th to 20th	Night	5% 14% 5% 10% 8% 5% 5% 5% 7% 8% 27%	2493
	21st to end	Night	3 14% 5% 11% 7% 7% 8% 4 6% 7% 29%	2017
March	1st to 10th	Night	3 9% 4 15% 9% 8% 6% 5% 5% 6% 29%	3736
	11th to 20th	Night	6% 12% 4 10% 6% 6% 5% 4 7% 10% 31%	3644
	21st to end	Night	5% 10% 3 10% 5% 5% 5% 4 6% 8% 38%	3550
April	1st to 10th	Night	4 9% 4 10% 8% 7% 6% 5% 7% 9% 30%	1900
	11th to 20th	Night	8% 11% 4 8% 6% 6% 5% 5% 7% 8% 32%	1659
	21st to end	Night	12% 10% 5% 9% 5% 5% 5% 4 6% 6% 34%	1520
May	1st to 10th	Night	6% 7% 3 10% 6% 6% 7% 6% 7% 8% 34%	2540
	11th to 20th	Night	9% 8% 3 7% 6% 5% 6% 5% 5% 8% 39%	2057
	21st to end	Night	10% 9% 4 10% 6% 6% 6% 5% 8% 9% 27%	2066
June	1st to 10th	Night	12% 9% 3 8% 6% 6% 6% 5% 7% 7% 32%	1140
	11th to 20th	Night	15% 9% 4 10% 7% 4 5% 4 6% 8% 28%	1140
	21st to end	Night	11% 7% 3 7% 6% 4 6% 5% 5% 7% 39%	1140
July	1st to 10th	Night	10% 5% 2 5% 4 5% 6% 5% 6% 7% 46%	1900
	11th to 20th	Night	7% 4 2 6% 5% 4 5% 7% 7% 8% 45%	1900
	21st to end	Night	10% 5% 2 6% 5% 6% 6% 5% 8% 9% 39%	2253
August	1st to 10th	Night	8% 4 2 5% 5% 4 4 4 7% 7% 49%	2459
	11th to 20th	Night	11% 5% 2 6% 5% 4 5% 4 7% 9% 42%	2497
	21st to end	Night	10% 5% 2 7% 5% 5% 6% 5% 8% 9% 38%	3037
September	1st to 10th	Night	13% 7% 3 6% 4 4 5% 3 7% 7% 40%	1900
	11th to 20th	Night	11% 6% 3 7% 5% 4 4 4 5% 8% 42%	1900
	21st to end	Night	10% 8% 2 8% 6% 5% 5% 5% 6% 7% 39%	2148
October	1st to 10th	Night	11% 13% 4 9% 5% 5% 5% 4 5% 7% 32%	3800
	11th to 20th	Night	8% 8% 2 7% 5% 6% 6% 4 6% 8% 41%	3979
	21st to end	Night	9% 12% 4 10% 6% 6% 6% 4 6% 6% 31%	4625
November	1st to 10th	Night	13% 13% 5% 10% 5% 4 4 3 6% 8% 29%	2745
	11th to 20th	Night	8% 17% 5% 11% 6% 6% 4 4 5% 7% 28%	3000
	21st to end	Night	7% 14% 5% 12% 8% 5% 5% 4 6% 7% 28%	3125
December	1st to 10th	Night	8% 14% 5% 10% 6% 5% 5% 4 6% 7% 29%	5220
	11th to 20th	Night	8% 16% 5% 13% 9% 7% 5% 4 5% 6% 23%	5930
	21st to end	Night	4 10% 5% 10% 6% 6% 6% 4 7% 8% 34%	7964

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	60% 5% 9% 15% 10%	2719
	11th to 20th	Day	56% 4 13% 16% 10% 1	2858
	21st to end	Day	45% 8% 21% 18% 8% 1	3498
February	1st to 10th	Day	53% 7% 13% 14% 12% 1	1556
	11th to 20th	Day	52% 8% 15% 17% 7% 1	1581
	21st to end	Day	55% 8% 11% 19% 7% 1	1437
March	1st to 10th	Day	53% 6% 10% 20% 11%	3138
	11th to 20th	Day	46% 8% 12% 23% 11%	3332
	21st to end	Day	50% 8% 13% 21% 8%	4103
April	1st to 10th	Day	47% 9% 14% 19% 10%	2280
	11th to 20th	Day	51% 7% 13% 19% 10% 1	2467
	21st to end	Day	52% 7% 12% 21% 7% 1	2660
May	1st to 10th	Day	41% 7% 15% 24% 11% 1	4420
	11th to 20th	Day	45% 7% 12% 24% 12% 1	4839
	21st to end	Day	51% 9% 12% 18% 8% 2	5510
June	1st to 10th	Day	47% 9% 13% 21% 9% 1	3040
	11th to 20th	Day	56% 7% 10% 20% 7%	3040
	21st to end	Day	44% 9% 15% 23% 10%	3040
July	1st to 10th	Day	35% 5% 12% 24% 22% 2	4981
	11th to 20th	Day	33% 6% 15% 30% 15% 1	4973
	21st to end	Day	39% 6% 21% 28% 6% 1	5116
August	1st to 10th	Day	35% 6% 16% 34% 10%	4452
	11th to 20th	Day	43% 4 16% 24% 13% 1	4372
	21st to end	Day	41% 6% 25% 24% 4	4623
September	1st to 10th	Day	41% 7% 22% 24% 5% 1	2280
	11th to 20th	Day	40% 7% 19% 28% 6%	2280
	21st to end	Day	43% 9% 17% 23% 8% 1	2031
October	1st to 10th	Day	52% 4 17% 22% 6% 1	3180
	11th to 20th	Day	48% 4 16% 27% 4	2952
	21st to end	Day	47% 5% 23% 21% 5%	2927
November	1st to 10th	Day	54% 6% 15% 20% 5% 1	1533
	11th to 20th	Day	55% 7% 16% 16% 7%	1400
	21st to end	Day	56% 6% 12% 18% 7% 1	1271
December	1st to 10th	Day	63% 6% 16% 9% 6% 1	1960
	11th to 20th	Day	64% 5% 14% 13% 4	2264
	21st to end	Day	40% 5% 17% 27% 10% 2	2992
January	1st to 10th	Night	57% 5% 10% 16% 11% 1	7226
	11th to 20th	Night	52% 6% 13% 16% 12% 1	7134
	21st to end	Night	51% 7% 16% 17% 9%	7458
February	1st to 10th	Night	56% 6% 13% 16% 9% 1	2733
	11th to 20th	Night	53% 7% 12% 20% 7% 1	2495
	21st to end	Night	53% 6% 13% 18% 8% 1	2017
March	1st to 10th	Night	54% 6% 11% 18% 11% 1	3736
	11th to 20th	Night	45% 10% 16% 19% 10%	3645
	21st to end	Night	39% 9% 14% 26% 12%	3550
April	1st to 10th	Night	47% 7% 14% 20% 11% 1	1900
	11th to 20th	Night	47% 5% 13% 23% 11% 1	1659
	21st to end	Night	48% 8% 10% 23% 10% 2	1520
May	1st to 10th	Night	42% 10% 12% 21% 13% 3	2540
	11th to 20th	Night	39% 8% 11% 28% 12% 2	2057
	21st to end	Night	46% 10% 13% 23% 8% 1	2066
June	1st to 10th	Night	48% 7% 11% 24% 10% 1	1140
	11th to 20th	Night	53% 7% 10% 22% 7% 1	1140
	21st to end	Night	40% 9% 17% 23% 11% 1	1140
July	1st to 10th	Night	35% 6% 13% 29% 17% 1	1870
	11th to 20th	Night	33% 7% 16% 25% 18% 1	1864
	21st to end	Night	38% 7% 21% 27% 6%	2182
August	1st to 10th	Night	33% 7% 17% 32% 10%	2452
	11th to 20th	Night	38% 5% 13% 29% 14% 1	2521
	21st to end	Night	41% 5% 29% 21% 4	3037
September	1st to 10th	Night	41% 8% 19% 24% 7% 1	1900
	11th to 20th	Night	39% 6% 18% 30% 6%	1900
	21st to end	Night	42% 8% 16% 22% 11% 1	2148
October	1st to 10th	Night	52% 5% 14% 20% 8% 1	3800
	11th to 20th	Night	41% 5% 17% 30% 7%	3979
	21st to end	Night	52% 5% 15% 22% 5%	4625
November	1st to 10th	Night	53% 7% 13% 22% 5% 1	2745
	11th to 20th	Night	56% 7% 13% 18% 7%	3000
	21st to end	Night	54% 6% 13% 20% 6% 1	3125
December	1st to 10th	Night	55% 5% 16% 17% 6% 1	5220
	11th to 20th	Night	62% 5% 15% 13% 5%	5927
	21st to end	Night	47% 5% 16% 25% 6% 1	7964

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	14% 10% 31% 30% 11% 6%	200
	11th to 20th	Day	17% 16% 31% 26% 10% 2	200
	21st to end	Day	14% 18% 30% 20% 14% 4	220
February	1st to 10th	Day	16% 12% 30% 25% 15% 3	190
	11th to 20th	Day	15% 15% 27% 24% 15% 3	273
	21st to end	Day	13% 15% 36% 24% 11% 1	319
March	1st to 10th	Day	12% 19% 27% 26% 13% 4	460
	11th to 20th	Day	13% 16% 34% 24% 11% 2	460
	21st to end	Day	18% 16% 27% 25% 13% 1	506
April	1st to 10th	Day	12% 19% 35% 22% 10% 2	460
	11th to 20th	Day	16% 19% 27% 23% 12% 4	452
	21st to end	Day	18% 18% 31% 19% 13% 2	460
May	1st to 10th	Day	17% 17% 33% 23% 8% 2	463
	11th to 20th	Day	14% 12% 24% 28% 17% 3	749
	21st to end	Day	15% 13% 23% 29% 17% 4	940
June	1st to 10th	Day	16% 15% 31% 22% 14% 3	870
	11th to 20th	Day	19% 11% 25% 25% 16% 3	870
	21st to end	Day	15% 9% 24% 24% 20% 7%	870
July	1st to 10th	Day	14% 8% 25% 28% 21% 4	856
	11th to 20th	Day	13% 9% 27% 26% 20% 6%	852
	21st to end	Day	12% 11% 28% 30% 15% 5%	832
August	1st to 10th	Day	14% 12% 20% 29% 19% 7%	531
	11th to 20th	Day	14% 16% 28% 22% 14% 5%	477
	21st to end	Day	16% 15% 30% 21% 13% 5%	539
September	1st to 10th	Day	18% 12% 29% 20% 16% 5%	490
	11th to 20th	Day	18% 13% 28% 24% 11% 5%	490
	21st to end	Day	13% 25% 30% 21% 10% 1	490
October	1st to 10th	Day	26% 15% 27% 19% 10% 3	490
	11th to 20th	Day	18% 15% 33% 23% 11% 1	371
	21st to end	Day	18% 15% 27% 24% 12% 3	277
November	1st to 10th	Day	21% 14% 31% 23% 10% 2	200
	11th to 20th	Day	22% 14% 32% 24% 8% 2	200
	21st to end	Day	20% 17% 27% 24% 10% 4	200
December	1st to 10th	Day	11% 22% 27% 28% 10% 3	200
	11th to 20th	Day	17% 14% 19% 34% 18%	200
	21st to end	Day	11% 12% 25% 29% 18% 5%	220
January	1st to 10th	Night	12% 11% 28% 32% 14% 2	1100
	11th to 20th	Night	14% 17% 25% 32% 11% 1	1059
	21st to end	Night	20% 19% 29% 24% 8% 1	990
February	1st to 10th	Night	16% 14% 21% 28% 17% 4	781
	11th to 20th	Night	13% 14% 28% 30% 14% 2	744
	21st to end	Night	7% 12% 31% 29% 18% 3	628
March	1st to 10th	Night	8% 13% 26% 33% 17% 3	760
	11th to 20th	Night	12% 10% 30% 32% 14% 2	760
	21st to end	Night	12% 9% 24% 31% 21% 3	836
April	1st to 10th	Night	9% 10% 29% 30% 18% 3	760
	11th to 20th	Night	12% 11% 30% 29% 15% 3	531
	21st to end	Night	16% 14% 28% 26% 15% 1	380
May	1st to 10th	Night	12% 14% 26% 32% 13% 3	380
	11th to 20th	Night	12% 10% 26% 31% 19% 2	374
	21st to end	Night	16% 9% 23% 27% 21% 3	411
June	1st to 10th	Night	13% 10% 27% 31% 17% 2	380
	11th to 20th	Night	19% 6% 23% 31% 18% 3	380
	21st to end	Night	15% 7% 22% 33% 21% 2	380
July	1st to 10th	Night	14% 6% 21% 35% 23% 1	370
	11th to 20th	Night	12% 6% 25% 31% 21% 5%	368
	21st to end	Night	10% 6% 24% 37% 21% 3	416
August	1st to 10th	Night	10% 4 19% 31% 30% 6%	378
	11th to 20th	Night	10% 10% 25% 32% 21% 2	376
	21st to end	Night	13% 7% 28% 30% 19% 2	557
September	1st to 10th	Night	17% 9% 21% 35% 16% 2	760
	11th to 20th	Night	15% 7% 24% 30% 21% 3	760
	21st to end	Night	15% 18% 28% 26% 11% 3	760
October	1st to 10th	Night	20% 13% 26% 28% 13% 1	760
	11th to 20th	Night	16% 14% 31% 27% 11% 1	760
	21st to end	Night	21% 15% 31% 25% 7% 1	836
November	1st to 10th	Night	19% 13% 28% 25% 13% 2	795
	11th to 20th	Night	17% 17% 30% 28% 8% 1	1000
	21st to end	Night	15% 15% 31% 28% 10% 1	1063
December	1st to 10th	Night	14% 14% 32% 29% 10% 1	1100
	11th to 20th	Night	15% 15% 28% 27% 14% 2	1100
	21st to end	Night	13% 11% 26% 33% 14% 2	1210

Page generated at 2025-02-03 01:05:52. Version ac07

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