Mosquito predictions

[BlueMan]

Hello! I'm trying to guess-timate when Sierra mosquitoes won't be that bad. Tuolomne Meadows is the main goal. I dearly hate the flying monsters. Anyone care to guess when the mosquitoes will die off? Is it futile to try and go early in the season and do my thing before the flying hordes hatch? My ideas were to try and go early (June) or later say late July or early August. I don't think I've ever been in the Sierra in such a dry year so I have no idea what to expect.

[c9h13no3]

Hello! I'm trying to guess-timate when Sierra mosquitoes won't be that bad. Tuolomne Meadows is the main goal. I dearly hate the flying monsters. Anyone care to guess when the mosquitoes will die off? Is it futile to try and go early in the season and do my thing before the flying hordes hatch? My ideas were to try and go early (June) or later say late July or early August. I don't think I've ever been in the Sierra in such a dry year so I have no idea what to expect.

Not futile to go early. They're usually not bad in May. Early June, the mozzies could be bad in Tuolumne, but I'd expect the first week would be okay. Especially if you camped up higher with less water/more wind.

Last week of July/first of August is probably about right for things to dry out. There will still be mosquitoes in wet areas, but it won't be man-eating hordes. I'd guess peak mosquito would be from the 20th of June until the 3rd week of July. But again, can change quickly with the weather & elevation. The mosquitoes were pretty bad in the Santa Cruz mountains at 3000' last weekend :P.

[Slow_AF]

I recall during the drought years 2012-15 I noticed bigger spikes around the first week of July. But my memory ain’t the best

[Matthewkphx]

I hiked the JMT southbound starting June 15, 2015 (a similarly dry year). Mosquitos were bad around Cathedral Lake but very tolerable through Tuolumne Meadows and Lyell Canyon. I don’t know if we got there before or after the peak season. I hit far, far worse mosquitos in Sabrina Basin in mid-July 2016.

Good luck on your trip.

[SSSdave]

https://onlinelibrary.wiley.com/doi/epd ... jvec.12340

Numbers of mosquitoes at elevations above 6k are driven more by the amount of snow melt shallow water atop landscapes, microclimates, and the end of hard freezes than calendar dates. A good sign for the near future is there is currently a cold system across the range dropping snow below 6k that is common in late May as many MD holiday backpackers experienced over decades are well aware of. When such late spring freezing occurs, it may kill mosquito larvae/pupa in shallow water and while air temperatures are also cold tends to inhibit hatched mosquitoes from swarming in clouds before flying to higher elevations where by instinct they expect to find more surface waters for egg laying.

Mosquitoes eggs require on average a couple weeks to hatch but may just be a week in warmer water. Thus a hard freeze may only reduce mosquito populations for a couple weeks before a new egg cycle hatches. Understanding how cold air forms and flows has value regarding mosquitoes during late spring as some areas receive regular sumping flows of cold radiation cooled air as with the bottom of canyons while higher slopes on canyon walls are out of such flows. Shallow pools in deep shading forest won't be as cold at night due to nearby moderating radiation from trees and vegetation as those waters out in the open bedrock. By mid summer even an occasional night freeze is unlikely to kill mosquitoes because landscapes have warmed up so are less affected by the diurnal atmosphere changes where mosquitoes just need to find some moderated vegetation to overnight within. After mosquitoes hatch subsequent hatches of dragonflies and damselflies can readily decrease numbers. Much more of course. Key is understanding where snow melt is currently putting shallow water atop landscapes, that can in this era be gleaned from looking at the SH satellite image complemented by caltopo for understanding the nature of microclimates.

In 2017 I backpacked from in late June from about 5k into Emigrant Basin areas below 8000 feet that sometimes have notorious densities at that time. I timed the trip following a late spring cold snow storm. There were plenty of mosquitoes below 6000 feet where temperatures were always above freezing while areas above where dustings of snow occurred were mosquito free that was probably not the case before that storm.

https://www.davidsenesac.com/2017_Trip_ ... 17-12.html

[rgliebe]

I just finished a full week of backpacking in Yosemite from 4500 to 8000 feet, and I saw about two dozen mosquitoes the entire time, and I was camped by creeks every night. The drought combined with cold weather has hit them hard. The storm that passed through last Friday and Saturday brought subfreezing temperatures down to 5000 feet, likely killing the few that were alive. New ones will hatch as the snow melts, but this year should be better than most. I spent most of yesterday on the valley floor at 4000 feet, and I saw a handful of mosquitoes only in one area by Tenaya Creek where the water was moving slowly. It was truly unusual for this time of year. If you don't want to wait for them to die out in August, go as soon as you can get access to the trailhead and live with some snow. I prefer snow over mosquitoes, plus daytime temperatures are more mild now than in August. The final hour or two of daylight is usually when they are at their worst, so if you go to bed early and wake up when the sun comes up and it is freezing, you'll miss a lot of them.