Driftwood Provincial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Driftwood Provincial Park clear sky chart from 2005-11-06 to 2025-01-07.

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	17% 12% 4 9% 5% 5% 4 3 5% 6% 30%	105773
	Night	17% 13% 4 10% 5% 5% 4 3 5% 6% 28%	103234
Transparency	Day	32% 44% 6% 13% 5%	109318
	Night	34% 44% 7% 11% 5%	107779
Seeing	Day	24% 15% 30% 20% 9% 3	14894
	Night	25% 12% 27% 26% 10% 1	23725

By Month

Percentage Cloud Cover NE (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	16% 19% 8% 15% 7% 5% 3 3 4 4 17%	2565
	11th to 20th	Day	12% 15% 6% 20% 8% 5% 4 3 3 6% 19%	2520
	21st to end	Day	16% 21% 8% 13% 6% 5% 4 2 4 4 18%	3010
February	1st to 10th	Day	10% 16% 7% 15% 10% 6% 5% 4 4 5% 18%	1710
	11th to 20th	Day	11% 18% 6% 13% 6% 6% 5% 4 3 5% 23%	1663
	21st to end	Day	17% 16% 6% 10% 6% 5% 5% 4 4 4 23%	1470
March	1st to 10th	Day	20% 18% 5% 8% 4 3 4 3 4 5% 26%	3298
	11th to 20th	Day	11% 17% 6% 13% 7% 5% 4 3 4 4 26%	3480
	21st to end	Day	13% 9% 4 8% 5% 6% 5% 3 4 5% 39%	3899
April	1st to 10th	Day	22% 13% 4 8% 4 4 4 2 4 5% 28%	2280
	11th to 20th	Day	21% 12% 3 7% 4 4 3 3 5% 5% 33%	2288
	21st to end	Day	21% 12% 3 8% 5% 4 4 3 4 5% 33%	2470
May	1st to 10th	Day	20% 11% 3 7% 4 5% 4 3 6% 7% 30%	4384
	11th to 20th	Day	17% 8% 3 7% 4 4 4 4 6% 8% 34%	4398
	21st to end	Day	18% 7% 2 6% 5% 4 5% 3 5% 7% 37%	4837
June	1st to 10th	Day	20% 9% 3 8% 5% 6% 4 4 5% 6% 30%	2660
	11th to 20th	Day	15% 6% 2 6% 6% 5% 6% 5% 5% 8% 38%	2768
	21st to end	Day	19% 7% 3 7% 6% 5% 5% 3 6% 7% 32%	2850
July	1st to 10th	Day	15% 7% 3 8% 6% 6% 5% 4 6% 7% 32%	4699
	11th to 20th	Day	13% 6% 3 7% 5% 5% 5% 5% 6% 9% 36%	4440
	21st to end	Day	11% 6% 2 6% 4 4 4 4 6% 8% 45%	4814
August	1st to 10th	Day	13% 7% 3 8% 5% 6% 6% 5% 7% 8% 32%	4185
	11th to 20th	Day	17% 6% 2 6% 5% 4 5% 4 6% 8% 35%	4044
	21st to end	Day	10% 6% 2 7% 5% 5% 6% 4 7% 9% 39%	4309
September	1st to 10th	Day	16% 8% 2 7% 5% 4 4 3 5% 7% 42%	2280
	11th to 20th	Day	14% 8% 3 7% 4 4 4 3 5% 6% 42%	2280
	21st to end	Day	22% 8% 3 6% 4 5% 3 3 5% 7% 34%	1983
October	1st to 10th	Day	20% 10% 3 8% 4 4 4 4 5% 6% 33%	1900
	11th to 20th	Day	25% 14% 3 8% 5% 4 4 3 5% 5% 23%	1900
	21st to end	Day	28% 15% 4 9% 4 4 5% 3 4 4 20%	2015
November	1st to 10th	Day	18% 14% 5% 9% 4 4 4 3 5% 5% 29%	1628
	11th to 20th	Day	18% 17% 7% 11% 6% 5% 4 3 4 4 21%	1600
	21st to end	Day	26% 19% 7% 12% 6% 4 4 2 4 3 14%	1600
December	1st to 10th	Day	18% 22% 6% 13% 7% 5% 6% 4 5% 4 12%	2600
	11th to 20th	Day	15% 21% 7% 14% 7% 4 3 2 2 4 20%	2986
	21st to end	Day	20% 21% 7% 15% 6% 4 4 2 2 4 15%	3960
January	1st to 10th	Night	16% 20% 7% 14% 8% 5% 4 3 4 5% 13%	4514
	11th to 20th	Night	12% 14% 6% 17% 9% 6% 5% 4 5% 5% 17%	4440
	21st to end	Night	12% 23% 8% 13% 6% 7% 4 3 3 4 16%	4628
February	1st to 10th	Night	13% 15% 6% 12% 9% 6% 4 4 5% 6% 21%	2470
	11th to 20th	Night	14% 14% 6% 12% 7% 5% 5% 3 5% 5% 24%	2403
	21st to end	Night	15% 17% 4 11% 7% 6% 4 3 4 6% 22%	1982
March	1st to 10th	Night	17% 15% 5% 8% 5% 4 4 3 4 5% 30%	3540
	11th to 20th	Night	14% 18% 6% 11% 5% 5% 4 3 5% 5% 23%	3479
	21st to end	Night	13% 9% 5% 11% 5% 5% 5% 4 5% 6% 33%	3732
April	1st to 10th	Night	21% 12% 4 7% 4 4 5% 3 4 5% 30%	1900
	11th to 20th	Night	20% 10% 4 7% 4 4 3 3 5% 4 36%	1857
	21st to end	Night	23% 9% 3 7% 5% 4 4 4 5% 5% 31%	1710
May	1st to 10th	Night	22% 10% 2 6% 4 5% 5% 4 5% 6% 32%	2554
	11th to 20th	Night	16% 9% 3 7% 5% 5% 4 4 4 6% 35%	2495
	21st to end	Night	13% 9% 2 9% 5% 4 4 4 5% 7% 38%	2738
June	1st to 10th	Night	17% 8% 3 8% 5% 5% 4 4 6% 6% 34%	1520
	11th to 20th	Night	16% 6% 2 5% 5% 4 4 4 6% 8% 40%	1405
	21st to end	Night	18% 7% 2 6% 5% 4 4 4 6% 8% 35%	1330
July	1st to 10th	Night	14% 6% 3 9% 5% 4 5% 3 6% 7% 37%	2263
	11th to 20th	Night	15% 7% 3 6% 4 4 4 4 5% 7% 40%	2520
	21st to end	Night	10% 6% 2 5% 3 5% 4 3 6% 7% 48%	2739
August	1st to 10th	Night	13% 5% 2 6% 4 4 5% 4 6% 8% 44%	2728
	11th to 20th	Night	16% 6% 2 6% 4 4 4 4 6% 7% 40%	2785
	21st to end	Night	14% 5% 1 6% 4 4 4 4 7% 8% 42%	3314
September	1st to 10th	Night	13% 6% 2 5% 3 4 4 4 5% 7% 47%	1900
	11th to 20th	Night	15% 6% 2 6% 5% 3 4 3 4 6% 46%	1900
	21st to end	Night	20% 8% 2 6% 3 4 4 3 4 7% 39%	2194
October	1st to 10th	Night	20% 9% 3 7% 4 4 4 3 5% 6% 36%	2280
	11th to 20th	Night	24% 13% 3 8% 5% 4 4 3 4 6% 27%	2280
	21st to end	Night	27% 13% 3 8% 4 5% 4 2 5% 5% 24%	2582
November	1st to 10th	Night	19% 14% 4 8% 5% 4 4 3 5% 5% 30%	2668
	11th to 20th	Night	20% 16% 4 10% 7% 5% 3 3 5% 5% 23%	2800
	21st to end	Night	25% 17% 5% 12% 6% 4 3 3 3 5% 16%	2800
December	1st to 10th	Night	19% 22% 6% 13% 7% 5% 5% 4 4 5% 10%	4580
	11th to 20th	Night	18% 18% 6% 14% 6% 5% 3 2 4 4 20%	5208
	21st to end	Night	23% 19% 5% 15% 6% 4 3 2 3 4 15%	6996

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	49% 36% 7% 5% 3	2566
	11th to 20th	Day	46% 36% 7% 8% 3	2520
	21st to end	Day	47% 39% 5% 7% 2	3010
February	1st to 10th	Day	25% 65% 4 4 2	1710
	11th to 20th	Day	24% 64% 3 6% 4	1672
	21st to end	Day	23% 64% 2 5% 4	1470
March	1st to 10th	Day	40% 39% 6% 8% 7% 1	3301
	11th to 20th	Day	39% 39% 6% 9% 7% 1	3480
	21st to end	Day	29% 39% 5% 16% 10% 1	3899
April	1st to 10th	Day	22% 65% 2 6% 4 1	2280
	11th to 20th	Day	21% 65% 2 8% 4 1	2288
	21st to end	Day	20% 64% 3 6% 6% 1	2470
May	1st to 10th	Day	35% 39% 4 17% 4	4398
	11th to 20th	Day	29% 39% 8% 20% 4	4402
	21st to end	Day	32% 39% 8% 11% 10% 1	4837
June	1st to 10th	Day	20% 65% 3 9% 4 1	2660
	11th to 20th	Day	18% 65% 4 7% 5% 1	2768
	21st to end	Day	18% 64% 4 8% 5%	2850
July	1st to 10th	Day	33% 38% 8% 16% 5%	4626
	11th to 20th	Day	28% 37% 11% 21% 4	4365
	21st to end	Day	22% 36% 10% 24% 8%	4661
August	1st to 10th	Day	30% 39% 7% 19% 4	4171
	11th to 20th	Day	30% 39% 9% 17% 5%	4083
	21st to end	Day	22% 39% 7% 24% 6% 1	4309
September	1st to 10th	Day	18% 60% 6% 10% 6%	2280
	11th to 20th	Day	15% 59% 7% 12% 6%	2280
	21st to end	Day	18% 60% 6% 11% 5%	1983
October	1st to 10th	Day	37% 38% 6% 17% 3	3160
	11th to 20th	Day	32% 39% 10% 16% 3	3140
	21st to end	Day	42% 38% 11% 8% 1	3305
November	1st to 10th	Day	32% 55% 5% 6% 2	1628
	11th to 20th	Day	30% 57% 4 7% 2	1600
	21st to end	Day	35% 56% 3 2 3	1600
December	1st to 10th	Day	51% 37% 4 7% 1	2600
	11th to 20th	Day	52% 31% 2 10% 5%	2986
	21st to end	Day	57% 26% 2 11% 4	3960
January	1st to 10th	Night	49% 35% 10% 5% 1	4514
	11th to 20th	Night	45% 36% 9% 8% 2	4440
	21st to end	Night	50% 38% 5% 4 2	4628
February	1st to 10th	Night	23% 65% 5% 5% 2	2470
	11th to 20th	Night	22% 63% 4 7% 4	2405
	21st to end	Night	23% 65% 3 5% 3 1	1982
March	1st to 10th	Night	34% 40% 9% 11% 6% 1	3550
	11th to 20th	Night	41% 39% 6% 9% 4	3480
	21st to end	Night	33% 40% 4 14% 8% 1	3732
April	1st to 10th	Night	21% 65% 3 6% 4	1900
	11th to 20th	Night	17% 65% 3 9% 6% 1	1857
	21st to end	Night	20% 65% 3 7% 5%	1710
May	1st to 10th	Night	35% 41% 6% 14% 5%	2560
	11th to 20th	Night	34% 40% 7% 16% 4	2496
	21st to end	Night	32% 39% 6% 15% 8% 1	2739
June	1st to 10th	Night	16% 65% 3 10% 5% 1	1520
	11th to 20th	Night	15% 65% 3 9% 7% 1	1405
	21st to end	Night	16% 63% 3 9% 7% 1	1330
July	1st to 10th	Night	35% 37% 8% 13% 7%	2227
	11th to 20th	Night	30% 37% 11% 18% 3	2472
	21st to end	Night	22% 36% 8% 24% 10%	2651
August	1st to 10th	Night	22% 39% 10% 21% 9%	2718
	11th to 20th	Night	31% 38% 10% 17% 5%	2812
	21st to end	Night	24% 38% 9% 19% 8% 2	3314
September	1st to 10th	Night	13% 62% 8% 12% 6%	1900
	11th to 20th	Night	15% 59% 5% 15% 5%	1900
	21st to end	Night	15% 60% 6% 13% 6%	2194
October	1st to 10th	Night	28% 37% 9% 18% 7%	3800
	11th to 20th	Night	32% 38% 10% 15% 5%	3779
	21st to end	Night	35% 38% 13% 9% 5%	4242
November	1st to 10th	Night	30% 56% 6% 5% 3	2668
	11th to 20th	Night	29% 57% 5% 8% 2	2800
	21st to end	Night	32% 57% 4 5% 2	2800
December	1st to 10th	Night	51% 38% 6% 4 1	4580
	11th to 20th	Night	50% 31% 4 7% 8%	5208
	21st to end	Night	55% 26% 3 10% 6%	6996

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	26% 21% 31% 18% 4 1	192
	11th to 20th	Day	24% 17% 36% 17% 4 2	180
	21st to end	Day	25% 15% 35% 17% 7% 1	267
February	1st to 10th	Day	24% 24% 34% 11% 4 1	270
	11th to 20th	Day	26% 25% 38% 11%	270
	21st to end	Day	32% 22% 30% 14% 2	282
March	1st to 10th	Day	24% 18% 37% 17% 4	460
	11th to 20th	Day	26% 16% 33% 20% 4 1	460
	21st to end	Day	29% 20% 28% 17% 6% 1	506
April	1st to 10th	Day	30% 18% 30% 16% 6% 1	460
	11th to 20th	Day	31% 17% 25% 16% 8% 2	452
	21st to end	Day	30% 17% 28% 16% 8% 1	460
May	1st to 10th	Day	27% 13% 31% 18% 8% 3	463
	11th to 20th	Day	26% 15% 25% 20% 10% 4	487
	21st to end	Day	22% 14% 30% 23% 9% 2	529
June	1st to 10th	Day	25% 10% 32% 24% 7% 1	490
	11th to 20th	Day	17% 14% 32% 24% 10% 3	598
	21st to end	Day	22% 15% 31% 20% 11% 1	680
July	1st to 10th	Day	14% 11% 32% 31% 11% 2	637
	11th to 20th	Day	14% 10% 34% 26% 13% 3	484
	21st to end	Day	12% 9% 31% 31% 14% 4	532
August	1st to 10th	Day	17% 8% 31% 26% 13% 5%	486
	11th to 20th	Day	18% 7% 22% 27% 18% 8%	479
	21st to end	Day	18% 10% 29% 24% 14% 5%	539
September	1st to 10th	Day	20% 9% 29% 21% 13% 7%	490
	11th to 20th	Day	15% 11% 25% 23% 18% 8%	490
	21st to end	Day	23% 13% 24% 22% 14% 4	490
October	1st to 10th	Day	26% 16% 23% 20% 14% 2	490
	11th to 20th	Day	30% 18% 29% 16% 6% 1	490
	21st to end	Day	33% 16% 28% 18% 5%	499
November	1st to 10th	Day	31% 16% 33% 15% 5%	262
	11th to 20th	Day	23% 22% 37% 13% 5% 1	200
	21st to end	Day	37% 18% 32% 11% 2 1	200
December	1st to 10th	Day	32% 14% 38% 11% 6%	200
	11th to 20th	Day	32% 22% 34% 9% 3 2	200
	21st to end	Day	31% 20% 28% 15% 5% 1	220
January	1st to 10th	Night	29% 13% 33% 21% 5%	785
	11th to 20th	Night	28% 14% 28% 24% 6%	760
	21st to end	Night	19% 13% 30% 29% 9% 1	836
February	1st to 10th	Night	19% 18% 35% 22% 5% 1	760
	11th to 20th	Night	23% 17% 35% 20% 4 1	743
	21st to end	Night	26% 16% 29% 25% 4	628
March	1st to 10th	Night	22% 18% 29% 26% 4	760
	11th to 20th	Night	23% 17% 32% 21% 7%	760
	21st to end	Night	22% 15% 31% 24% 8% 1	836
April	1st to 10th	Night	29% 13% 29% 25% 4	760
	11th to 20th	Night	26% 15% 26% 24% 8%	733
	21st to end	Night	28% 10% 28% 23% 11% 1	570
May	1st to 10th	Night	25% 7% 26% 29% 12%	407
	11th to 20th	Night	22% 10% 28% 29% 11%	374
	21st to end	Night	19% 8% 30% 32% 11%	411
June	1st to 10th	Night	19% 7% 28% 37% 8%	380
	11th to 20th	Night	18% 7% 27% 35% 12% 1	380
	21st to end	Night	22% 6% 22% 34% 15% 1	380
July	1st to 10th	Night	11% 6% 29% 39% 14% 1	370
	11th to 20th	Night	15% 4 22% 42% 18%	368
	21st to end	Night	11% 5% 24% 40% 19%	416
August	1st to 10th	Night	16% 6% 20% 36% 21% 1	509
	11th to 20th	Night	13% 5% 17% 37% 26% 2	564
	21st to end	Night	17% 8% 25% 29% 18% 2	739
September	1st to 10th	Night	16% 7% 27% 30% 19% 2	760
	11th to 20th	Night	20% 6% 21% 26% 24% 3	760
	21st to end	Night	24% 9% 20% 29% 17% 2	760
October	1st to 10th	Night	24% 10% 27% 26% 13% 1	760
	11th to 20th	Night	32% 12% 26% 20% 8% 1	760
	21st to end	Night	35% 12% 25% 24% 4	836
November	1st to 10th	Night	30% 11% 24% 28% 6% 1	780
	11th to 20th	Night	29% 17% 29% 18% 8%	800
	21st to end	Night	37% 14% 22% 22% 5%	800
December	1st to 10th	Night	34% 16% 27% 17% 6%	800
	11th to 20th	Night	29% 15% 29% 23% 4 1	800
	21st to end	Night	35% 13% 25% 22% 4	880

Page generated at 2025-01-04 03:23:59. Version ac07

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